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https://archive.org/details/reconnaissanceof4434gran 


DEPARTMENT  OF  THE  INTERIOR 

UNITED  STATES  GEOLOGICAL  SURVEY 

GEORGE  OTIS  SMITH,  DIRECTOR 


BULLETINS 

Nos.  443-446 


WASHINGTON 

GOVERNMENT  PRINTING  OFFICE 
1911 


5^  7 

y.  "o 


CONTENTS 

Geological  Survey  bulletin  443;  Reconnaissance  of  geology  and  mineral  resources  of 
Prince  William  Sound,  Alaska. 

Same  444;  Bibliography  of  North  American  geology  for  1909,  with  subject  index. 
Same  445;  Geology  of  pegmatites  and  associated  rocks  of  Maine. 

Same  446;  Geology  of  Berners  Bay  region,  Alaska. 

Ill 


tb 


DEPARTMENT  OF  THE  INTERIOR 

UNITED  STATES  GEOLOGICAL  SURVEY 

GEORGE  OTIS  SMITH,  Director 


BuIjLETin  443 


RECONNAISSANCE 

OF  THE 

GEOLOGY  AND  MINERAL  RESOURCES 


PRINCE  WILLIAM  SOUND 
ALASKA 

BY 

U.  S.  GRANT  AND  D.  F.  HIGGINS 


WASHINGTON 

GOVERNMENT  PRINTING  OFFICE 

1910 


CONTENTS. 


Page. 

Preface  by  A.  H.  Brooks 7 

Introduction 9 

Location  and  geography 9 

Outline  of  the  geology 11 

Previous  explorations 12 

The  present  report 13 

Topography 14 

Mountains  and  peneplain 14 

Valleys  and  lowlands 15 

'General  description 15 

Recent  changes  of  level 17 

Glaciation 18 

Early  glaciation 18 

Present  glaciation 19 

General  geology 20 

Introduction 20 

Sedimentary  rocks 22 

V aldez  group 22 

General  description 22 

Age  and  correlation 23 

Orca  group 25 

General  description 25 

Special  descriptions 26 

Galena  Bay 26 

Ellamar  and  Bligh  Island 28 

Knight  Island 28 

Latouche  Island 29 

Hoodoo  Island 31 

Elrington  Island 31 

Age  and  correlation  of  the  Orca  group : 32 

Igneous  rocks 33 

Granites 33 

Granite  of  Ewan  Bay 34 

Eshamy  granite 34 

Nellie  Juan  granite 37 

Granite  of  Culross  Island 37 

Granite  of  Passage  Canal 38 

Esther  Granite 39 

Cedar  Bay  granite 41 

Sheep  Bay  granite 43 

Other  granite  areas 44 

Summary 44 

Acidic  dikes 46 


3 


4 


CONTENTS. 


General  geology — Continued.  Page. 

Igneous  rocks — Continued. 

Basic  intrusive  rocks 48 

Gabbros 49 

Gabbro  on  Esther  Island 49 

Gabbro  on  Latouche  Island 49 

Diabases 50 

Diabase  dikes  at  Valdez  Narrows 50 

Diabase  in  Tatitlek  Narrows 50 

Diabase  on  Unakwik  Inlet 50 

Greenstones 51 

Economic  geology 52 

Copper 52 

Historical  statement 52 

Ore  minerals 53 

Ore  bodies 54 

General  description 54 

Origin  of  the  ore  bodies 57 

Special  descriptions 59 

Galena  Bay 59 

Ellamar 59 

Boulder  Bay 61 

Landlocked  Bay j 61 

Standard  Copper  Mines  Company 62 

Three  Man  Mining  Company 62 

FidalgoBay 62 

Whalen  and  Nelson  prospect 62 

Fidalgo  Mining  Company 63 

Fidalgo  Alaska  Copper  Company 63 

Latouche  Island 63 

Bonanza  mine 63 

Reynolds- Alaska  Development  Company 66 

Latouche  Copper  Mining  Company 67 

Knight  Island 67 

Knights  Island  Consolidated  Copper  Company 67 

Russell  Ball  Copper  Company 68 

Happy  Jack  Copper  Mining  and  Development  Company 68 

Copper  Bullion  claims 69 

Knights  Island  Mining  and  Development  Company 69 

Orca  Inlet 70 

^ Summary. 70 

Prospecting 70 

Gold 71 

Placer  gold 71 

Gold-bearing  veins 71 

Port  Valdez,  by  Alfred  H.  Brooks 72 

McKinley  Lake 75 

Jackpot  Bay 76 

Conclusions 76 

Silver 77 

Nickel 77 

Antimony 78 

Lead 78 


CONTENTS. 


5 


Economic  geology — Continued.  Page. 

Zinc 78 

Iron 79 

Asbestos 79 

Petroleum 79 

Recent  Survey  publications  on  Alaska 80 

Index 87 


illustrations; 


Page. 

Plate  I.  Sketch  map  of  Prince  William  Sound 10 

II.  Geologic  reconnaissance  map  of  Prince  William  Sound In  pocket. 

III.  View  looking  northward  from  vicinity  of  Cordova 14 

IV.  Lowland  plain  between  Landlocked  and  Fidalgo  bays 16 

V.  The  Three  Giants,  Knight  Island 18 

VI.  A,  Glaciated  mountains  and  fiords,  Knight  Island;  B,  Elevated 

beach,'  Columbia  Bay 18 

VII.  A,  Slate  and  graywacke  of  Orca  group.  Gull  Island;  B,  Slate  over- 

lain  by  greenstone  near  Rocky  Point 24 

III.  A,  Ellipsoidal  greenstone  near  Rocky  Point;  B,  Sections  of  ellipsoi- 
dal greenstone  near  Rocky  Point 26 

IX.  Microphotographs 36 

X.  A,  Ellamar  mine  at  Ellamar ; B,  Dock  and  ore  bunkers  of  the  Stand- 
ard Copper  Mines  Company  on  Landlocked  Bay 60 

XI.  A,  Quarry  face  of  the  Bonanza  mine  on  Latouche  Island;  B,  Dock, 

ore  bunkers,  etc.,  of  the  Bonanza  mine  on  Latouche  Island 64 

XII.  Topographic  and  geologic  map  of  part  of  Latouche  Island In  pocket. 

Figure  1.  Interbedding  of  sediments  and  basic  lava  fiows,  Orca  group 27 

2.  Map  and  section  of  the  northeast  end  of  Latouche  Island 29 

3.  Sections  across  Latouche  Island 30 

4.  Plan  of  underground  workings  at  the  Ellamar  mine,  September,  1905 . 60 

5.  Bonanza  mine,  Latouche  Island 64 

6.  Plan  of  underground  workings  at  the  Bonanza  mine,  June,  1909 65 

7.  Duchess  tunnel,  Latouche  Island 66 

8.  Bald  Eagle  tunnel,  Knight  Island 68 

9.  Tunnel  cutting  five  schistose  ore-bearing  zones,  Knight  Island 69 


6 


PREFACE. 


By  Alfred  H.  Brooks. 


The  continued  progress  of  the  copper-mining  industry  on  Prince 
William  Sound  since  the  very  hasty  examination  of  this  field  in  1900 
by  Schrader  and  Spencer  has  led  to  a demand  for  further  investiga- 
tions. The  following  report  is  the  result  of  reconnaissance  surveys 
made  in  1905  and  in  1908,  which  complete  the  preliminary  work  in 
this  district.  Should  the  mining  interests  continue  to  develop,  de- 
tailed surveys  of  the  more  important  parts  of  the  field  will  be  under- 
taken as  soon  as  circumstances  permit. 

Altogether  a little  over  five  months  was  devoted  to  the  studies 
whose  results  are  here  submitted.  During  this  time  over  1,500  miles 
of  shore  line  was  examined  and  more  than  a hundred  prospects  and 
mines  were  visited,  some  of  which  were  surveyed  in  considerable  de- 
tail. Geologic  reconnaissance  mapping  was  carried  over  an  area  of 
about  6,000  square  miles'.  Detailed  work  was  also  done  in  the  north- 
ern half  of  Latouche  Island.  In  view  of  the  hasty  character  of  the 
work  and  the  intricacy  of  the  geology  it  could  not  be  expected  that 
final  results  on  all  the  many  problems  could  be  achieved.  Much  at- 
tention was  given  to  studying  the  economic  problems,  to  determine  as 
far  as  possible  the  general  laws  governing  the  occurrence  of  the  ore 
bodies.  Incidental  to  this  study,  facts  were  gathered  bearing  on  the 
occurrence  and  extent  of  individual  ore  bodies,  and  many  of  these 
are  presented  in  the  following  pages.. 

Those  who  expect  to  find  in  this  volume  an  exhaustive  statement 
of  the  mineral  occurrences  on  individual  properties  or  an  estimate  of 
their  extent  and  value  will  be  disappointed.  The  preparation  of  such 
reports  is  the  business  of  private  mining  experts,  rather  than  of  the 
Federal  Government.  It  is  believed,  however,  that  this  statement  of 
the  geology  of  the  region  will  be  of  great  benefit  to  the  mining 
interests. 

Among  the  important  results  here  set  forth  is  the  presence  of  two 
unconf ormable  rock  groups,  the  V aldez  and  the  Orea.  Though  this  was 
suggested  by  the  earlier  investigations  of  this  field,  the  definite  proof 
was  lacking.  Of  equal  importance  is  the  subdivision  of  the  Orca 

7 


8 


PREFACE. 


group  into  a lower  and  an  upper  member.  It  seems  possible  that  at 
least  the  lowest  Orca,  made  up  chiefly  of  greenstone  effusives,  may 
prove  to  be  of  the  same  age  as  the  Nikolai  greenstone  of  the  Chitina 
basin,  which  it  resembles  lithologically.  Copper  ores  are  associated 
with  both  these  greenstone  formations.  Another  result  of  these 
studies  is  the  evidence  of  very  close  folding  accompanied  by  fault- 
ing to  which  the  rocks  of  both  the  Orca  and  Valdez  groups  have  been 
subjected. 

The  important  fact  bearing  on  the  distribution  of  the  ore  bodies 
is  that  they  appear  to  be  found  only  in  the  rocks  of  the  Orca  group 
and,  indeed,  for  the  most  part  in  close  association  with  the  green- 
stone member.  Mr.  Grant  and  Mr.  Higgins  indicate  that  the  copper 
was  derived  from  the  greenstones,  a genesis  which  is  entirely  similar 
to  that  of  most  of  the  copper  ores  of  the  Chitina  ® and  White  River  ^ 
districts. 

“ Moffit,  P.  H.,  and  Maddren,  A.  G.,  Mineral  resources  of  the  Kotsina-Chitina  rej^ion  ; 
Bull.  U.  S.  Geol.  Survey  No.  374,  1909,  p.  51. 

^Moffit,  F.  H„  and  Knopf,  Adolph,  Mineral  resources  of  the  Nabesna-White  River  dis- 
tricts : Bull.  U.  S.  Geol.  Survey  No.  379,  1909,  p.  171. 


RECOMAISSANCE  OF  THE  GEOLOGY  AO  MINERAL 
RESOURCES  OF  PRINCE  WILLIAM  SOUND,  ALASKA. 


i 

By  IJ.  S.  Grant  and  D.  F.  Higgins. 


INTRODUCTION. 

LOCATION  AND  GEOGRAPHY. 

Prince  William  Sound,  formerly  known  by  the  Kiissians  as  Chiigach 
Gulf,  is  an  embayment  extending  northward  from  the  north  side  of 
the  Gulf  of  Alaska,  near  the  center.  The  sound  lies  west  of  the 
Copper  River  delta  and  east  of  Cook  Inlet,  between  west  longitude 
145°  37'  and  148°  43'  and  north  latitude  59°  4G'  and  61°  16'.  The 
extreme  east  and  west  length  of  the  sound,  from  the  head  of  Cordova 
Bay  on  the  east  to  the  head  of  Port  Nellie  Juan  (or  Kings  Bay)  on 
the  west,  is  105.6  miles,  and  its  extreme  north-south  dimension,  from 
the  head  of  College  Fiord  on  the  north  to  the  southern  extremity  of 
Montague  Island  on  the  south,  is  104  miles.  (See  Pis.  I and  II.) 

Prince  William  Sound  is  not  a sound  according  to  the  customary 
usage  of  that  term,  but  is  an  extensive  bay  or  gulf  which  includes 
many  islands.  The  coast  line  is  indented  by  numerous  long,  narrow 
inlets  or  fiords  and  by  other  less  regular  embayments  whose  shores 
are  commonly  of  great  irregularity.  The  approximate  amount  of 
mainland  shore  line  from  the  Copper  River  delta  to  Cape  Puget  is 
975  miles,  and  the  total  shore  line  of  the  islands  in  the  sound  is  nearly 
1,065  miles,  making  the  total  amount  of  shore  line  on  the  sound  ap- 
proximately 2,040  miles.  The  coast  is  rugged  and  rocky  and  in  many 
places  rises  abruptly  from  the  water’s  edge  to  altitudes  of  1,000  to 
3,000  feet.  A few  miles  inland  from  the  coast  are  mountains  from 
3,000  to  over  10,000  feet  in  altitude.  Mountains  uninterruptedly  sur- 
round the  sound  on  its  east,  north,  and  west  sides,  and  the  larger 
islands,  especially  Hawkins,  Hinchinbrook,  and  Montague,  which  lie 
along  the  south  side  of  the  sound,  are  also  mountainous.  There  are 
many  snow  fields  about  Prince  William  Sound,  and  from  these  fields 
glaciers  descend,  reaching  tide  water  in  a number  of  inlets  or  fiords 
on  the  north  and  west  sides  of  the  sound. 


9 


10  RECONNAISSANCE  OF  PRINCE  WILLIAM  SOUND,  AI^SKA. 


Key  to  Plate  I. 


Copper  Mines  and  Prospects. 

Ellamar  district. 

1.  Ellamar -mine. 

2.  McNaughton. 

3.  Rua  & Frodenburg:  Wagner;  Falck;  Sehage. 

4.  Reynolds-Alaska  Development  Co. 

5.  Fieldf'r  & Hemple. 

G.  Simonstad  & Hendrie. 

gjoalena  Bay  Mining  Co.  (Millard). 

9.  Tib  bits  & Wilson. 

10.  Copper  Crown. 

11.  Standard  Copper  MiningCo.  (Bourke  & Steele); 

Grove. 

12.  Hemple. 

13.  Reynolds-Alaska  Development  Co.;  Spaulding; 

Barre. 

ll.'l 

IgAThree  Man  Mining  Co.  (Dickey). 

l?!j 

18.  Dolan  & Rystrom;  Dolan  & Wagner. 

19.  Chisna  Consolidated  Copper  Co.  (Griffith). 

21.  Fidalgo  Alaska  Copper  Co.  (Schlosser). 

22.  Neversweat;  Manhattan. 

23.  Shamrock;  Arley;  Bratton. 

24.  Merchant,  Bell  & Larson;  Roosevelt;  Birdie. 

25.  Fidalgo  Mining  Co.  (Blakney);  Simonstad  & 

Larson. 

26.  Whalen  & Nelson. 

27.  Bratton. 

28.  Guthrie  & Bellola. 

..  Cordova  district. 

30.>Ellis,  Boone  & Ibeck. 

31.1 

32.  Kelly  & Macormac. 

33.  Flynn  & Scott  properties. 

34.  Kippin  & Co.;  Kinney;  Diggs. 

|g‘|Flynn  & Co. 

37.  Revenue. 

|g‘|Tansey  groups. 

4o!  — . 

41.  Flynn  & Co. 

^2’|Armstrong  Exploration  Co. 

44.  Dalton,  Boswell  & Lowe. 

45.  Cordova  Copper  Co. 

46.  Emerald. 

47.  Boswell  & Lowe. 

48.  Rosencrans  & Co. 

49.  Shepard  & Macpherson;  Kelly  & Van  Slack; 

Diggs  & Tremble;  Brown  & Collins;  McKenna 
& Kiffin;  Flynn  & Co. 

50.  Flynn  & Co. 

51.1Hanson  & Co.;  Flynn,  Holt,  Brown  & Collins; 
52./  Kelly,  Diggs,  McKenna  & Tremble. 

g^'  jwash  & Waskey. 

ggABoswell,  Holt  & Flynn. 

57.  Ibeck,  Ellis  & Boone;  McMurphy;  Diggs. 

58.  Scott  & Ibeck. 

59.  Harris;  Ibeck;  Richards. 

146.  Cordova-Tacoma  Copper  Co. 

Latouchc  Island  district. 

60.  Latouche  Consolidated  Copper  Co.  (Tibbits). 

61.  Seattle- Alaska  Copper  Co. 

G2  ^ 

gj^ALatouche  Island  Copper  MiningCo.  (Murphy). 

!|^'|Reynolds- Alaska  Development  Co. 

66. \Chicago-Latouche  Mining  and  Power  ('o.  (Ba- 

67. /  zard). 

68.  Bonanza  Mine. 

69.  Latouche  Copper  Mining  Co.  (Barrack). 

70.  . 

jyHogg. 

Knight  Island  district. 


81.  Hendrix,  Reavley  McMasters. 

82.  . 

g^  jcraham  & Harrison. 

85.  Betties. 

86.  Sponberg,  Sanberg  Simpson. 

87.  Larson. 

88.  Ericksen  & Allen. 

89.  Moore. 

90.  Hubbard  & Elliott. 

91.  Russell  Ball  Copper  Co. 

92.  Grove  & Walters. 

93.  Knights  Island  Copper  Mining  Co.  (Hemple). 

94.  Twentieth  Century  Knight  Island  Copper  Min- 

ing Co. 

95.  Knights  Island  Alaska  Copper  Co. 

96.  Hemple. 

97. \Knights  Island  Consolidated  Copper  Co.  (Hub- 

98. /  bard  & Elliott). 

99.  Copper  Bullion  (Rua). 

100. . 

101.  Wallace,  McPherson  & Valentine. 

102.  Fergusson,  Johnson  & Harvey. 

103.  Kaczanowski  & Wilson. 

104.  Wallace,  McPherson  & Valentine. 

105.  Big  Passage  Copper  Mining  Co. 

106.  Knights  Island  Mining  and  Development  Co. 

Igg'lcrown  Copper  Co.  (Bradford). 

109’.  Malack. 

110.  Boyle. 

111.  Malack. 

112.  Von  Gunther. 

113.  Singletary. 

Glacier  Island  district. 

116.  Glendinning  Mining  Co. 

117.  Byers. 

118.  Gilnow. 

119.  Chamberlain. 

120.  . 

121. . 

122.  Nelson  & Rystrom. 

123.  Jensen. 

124.  Jensen,  Walace  & Kilbourn. 

125.  Nelson. 

Seward  district. 

126.  Leitzke. 

127.  Pitman  & Gould. 

128.  Ellsworth;  Reynolds-Alaska  Development  Co. 

129.  Peterson. 

Pitman  & Gould. 

132.  Reynolds-Alaska  Development  Co. 

133.1 

134.  /Likes  & Frazer. 

135. J 

136.  Redman  & Guyot. 

137.  Shaw,  Deubruel  A Bouchaert. 

147.  Betties  & Evans. 

149. . 

Gold  Prospects. 

McKinley  Lake  {east  of  Cordova). 

1.39.  Armstrong  Exploration  Co. 

140.  Walker;  Erickson  Bros.;  Maloney;  Armstrong 

Exploration  Co. 

141.  Rice  Bros.;  Barclay  & Harris. 


20.  Benzer. 


Fidalgo  Bay. 
Port  Valdez. 


145.  ClilTmine. 

Jackpot  Ray. 

114.  Evans,  Cooper  A Matson. 


Seward. 


142.  Gould. 

143.  California-Alaska  Mining  Co. 

144.  Stephenson. 

150.  Fairman  & Madsen;  Gaydon. 

151.  Gilpatrick  claims. 


73.  Happy  Jack  Copper  Mining  and  Development 

Co. 

74.  Hogan,  Hemple  & Egan. 

^g'|james  Mullins  Coal  Co.  (Wilson). 

77.  Kilbourn. 

78.  Schultz. 

™:}Harvey. 


Antimony  Prospect. 

Port  Wells. 

115.  Bratten,  Daniels  & Coch. 

Nickel  Prospect. 

Unakwik  Inlet. 

148.  Smith. 


I TVT'^rpiinTTn’^r  rr » m 


MINERAL  RESOURCES  OF 


PRINCE  WILLIAM  SOUND  REGION,  ALASKA 

AND  ADJACENT  TERFITORY 
FROM 

RESURRECTION  BAY  TO  THE  COPPER  RIVER  DELTA 

Compiled  from  United  States  Coast  and  Geodetic  Survey 
charts;  published  maps  of  the  United  States  Geological  Sur- 
vey; and  material  sketched  by  U.  S.  Grant  and  D.  F.  Higgins 
for  the  United  States  Geological  Survey,  comprising  most  of  60 

the  west  and  north  sides  of  the  sound.  Solid  lines  indicate  ~ 00 
more  definite  information,  dotted  lines  are  approximate. 

5 0 5 IQ  15  20Mae^ 

1910 


LEGEND 

X Coppt>r  mine  or  piospect  with  extensive  developments 
• Copper  prospect 
D Gold  pn-ospect 
A Antimony  prospect 


6°3o'  146°00'  145®30' 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  443  PLATE 


INTRODUCTION. 


11 


The  principal  towns  of  the  district  are  Valdez  and  Cordova. 
Valdez  is  situated  at  the  northeast  corner  of  the  sound,  at  the  head  of 
Port  Valdez.  From  this  town  the  government  telegraph  line  and 
trail  lead  into  the  interior  of  Alaska,  and  three  railways  have  been 
projected  toward  the  Copper  River  district.  Up  to  September,  P)09, 
only  a small  amount  of  track  had  been  laid  on  these  railways.  Valdez 
is  the  outfitting  point  for  much  of  Prince  William  Sound  and  for  the 
Copper  River  and  Tanana  districts.  Cordova  is  situated  on  the 
southeastern  part  of  the  sound,  on  the  southeast  shore  of  Orca  Bay. 
It  is  the  tide- water  terminus  of  the  Copper  River  and  Northwestern 
Railway,  on  which  rails  had  been  laid  in  September,  1909,  to  a dis- 
tance of  about  100  miles.  Building  was  especially  active  at  Cordova 
during  the  summers  of  1908  and  1909.  Other  settlements  are  at  Orca, 
on  Orca  Bay;  Landlock,  on  Landlocked  Bay;  Ellamar,  on  Virgin 
Bay;  and  Latouche,  on  Latouche  Island.  There  are  mining  camps 
at  a number  of  points,  especially  on  Landlocked,  Boulder,  and 
Fidalgo  bays  and  on  Knight  and  Latouche  islands.  Indian  villages 
exist  as  follows:  Nuchek,  on  the  west  end  of  Hinchinbrook  Island; 
Tatitlek,  near  Ellamar;  Kiniklik,  on  the  north  side  of  the  sound 
between  Eaglek  Bay  and  Unakwik  Inlet ; and  Chenega,  near  the  south- 
east corner  of  Chenega  Island.  (See  Pis.  I and  II.) 

OUTLINE  OF  THE  GEOLOGY. 

The  sedimentary  rocks  of  Prince  William  Sound  are  separable  into 
two  divisions,  known  as  the  Valdez  group  and  the  Orca  group.  The 
Valdez  is  the  older,  and  outcrops  along  the  northern  part  of  the  sound, 
especially  on  the  shores  of  Port  Valdez.  This  group  is  composed  of 
slates  and  graywackes  which  have  been  closely  folded  and  meta- 
morphosed to  some  extent,  so  that  they  are  now  partly  crystallized. 
No  markedly  crystalline  schists  occur,  except  in  the  vicinity  of  gran- 
itic intrusions.  The  Orca  group  lies  unconformably  upon  the  Valdez 
and  has  been  much  folded,  though  not  as  closely  as  the  Valdez.  The 
Orca  group  consists  in  the  main  of  dark-colored  slates  and  gray- 
wackes, with  locally  much  greenstone;  conglomerates  and  incon- 
spicuous limestones  occur  in  some  places.  The  greenstones  are  to  a 
large  extent  altered  basic  lava  flows,  interstratified  with  slates  and 
graywackes.  The  peculiar  ellipsoidal  structure  of  these  greenstones 
is  a marked  characteristic  of  parts  of  the  Orca  group.  The  Orca 
rocks  occur  especially  on  the  eastern  and  southern  shores  of  the 
sound  and  on  the  islands  of  the  central  part  of  the  sound.  (See 
PI.  II.)  The  intrusive  rocks  of  the  district  consist  of  basic  dikes  and 
bosses  and  dikes  of  granite.  The  basic  dikes  are  apparently  of  Oa*ca 
age,  but  some  at  least  of  the  granites  cut  the  Orca  rocks.  The  age 
of  the  Valdez  and  Orca  groups  is  not  known;  the  Orca  is,  however, 
probably  Mesozoic  and  the  Valdez  perhaps  Paleozoic. 


12  RECONNAISSANCE  OF  PRINCE  WILLIAM  SOUND,  ALASKA. 

The  chief  mineral  deposits  of  Prince  William  Sound  are  copper 
ores.  The  ore  mineral  is  chalcopyrite,  with  which  pyrrhotite  usually 
occurs.  The  ore  deposits  are  mainly  in  shear  zones  in  the  greenstones 
or  in  the  slates  of  the  Orca  group  close  to  the  greenstones.  The 
important  copper  deposit  on  Latouche  Island  is,  however,  not  known 
to  be  intimately  associated  with  greenstone.  There  are  two  producing 
copper  mines  on  the  sound — the  Ellamar  mine,  at  Ellamar,  and  the 
Bonanza  mine,  on  Latouche  Island.  Copper  prospecting  has  been 
active,  especially  about  Boulder,  Landlocked,  and  Fidalgo  bays  and 
on  Knight  and  Latouche  islands. 

PREVIOUS  EXPLORATIONS. 

Prince  William  Sound  was  discovered  by  Capt.  James  Cook  in 
1778.  It  was  visited  by  Artega  in  1779,  Zaikof  in  1783,  Martinez 
in  1788,  Fidalgo  in  1790,  Malaspina  in  1791,  and  Vancouver  in  1791, 
and  later  by  other  explorers."  Vancouver  made  a reconnaissance  of 
much  of  the  sound  and  his  maps  were  of  value  for  over  one  hundred 
years.  The  Kussians  early  used  the  sound  as  trading  ground,  and 
a post  was  established  at  Kuchek,  on  the  west  end  of  Hinchinbrook 
Island,  about  1793.  These  early  explorers  gave  geographic  infor- 
mation concerning  the  district,  but  very  little  as  to  its  geology. 

The  first  geologic  exploration  of  Prince  William  Sound  was  under- 
taken by  Mendenhall  ^ and  Schrader  ^ in  1898.  Mendenhall  gave  an 
account  of  (1)  explorations  which  had  been  made  in  the  district,  (2) 
the  geography,  and  (3)  the  geology  of  Passage  Canal  and  Port  Wells, 
in  the  northwestern  part  of  the  sound.  He  described  the  Sunrise 
“ series  ’’  of  rocks  as  occupying  the  shores  of  this  part  of  the  sound 
and  as  extending  Avestward  to  Cook  Inlet.  Schrader  visited  points 
on  the  eastern  shore  of  Prince  William  Sound  between  Orca  and 
Valdez.  He  described  the  geology  and  geography  of  that  district 
and  named  the  Valdez  “series”  and  the  Orca  “series”  of  rocks. 
He  also  described  the  copper  prospects  on  Landlocked  Bay,  at  Ella- 
mar, and  on  Latouche  Island.  His  report  is  accompanied  by  a topo- 
graphic map  of  the  sound  and  by  a topographic  and  geologic  map 
of  Port  Valdez  and  the  district  to  the  northeast. 

The  Harriman  Alaska  Expedition  visited  Prince  Wiliam  Sound 
in  1899.  The  Columbia  Glacier  and  the  glaciers  of  College  and  Har- 
riman fiords  were  described  in  detail.'^  Information  concerning  the 
geology  and  ore  deposits  was  obtained  and  the  main  rocks  of  the 

“ Brooks,  A.  H.,  The  geography  and  geology  of  Alaska  : Prof.  Paper  U.  S.  Geol.  Survey 
No.  45,  1006,  pp.  109-113. 

Mendenhall,  W.  C.,  A reconnaissance  from  Resurrection  Bay  to  the  Tanana  River, 
Alaska,  in  1898:  Twentieth  Ann.  Rept.  U.  S.  Geol.  Survey,  pt.  7,  1900,  pp.  265-340. 

f Schrader,  F.  C.,  A reconnaissance  of  a part  of  Prince  William  Sound  and  the  Copper 
River  district,  Alaska,  in  1898  ; Idem,  pp.  341^23. 

^ Gilbert,  G.  K.,  Harriman  Alaska  Expedition,  vol.  3,  1904. 


INTRODUCTION. 


13 


sound  were  referred  to  the  Vancouver  “ series,”  regarded  as  Lower 
Jurassic  in  age.® 

Schrader  and  Spencer^  examined  more  in  detail  parts  of  Prince 
William  Sound  in  1900  and  described  the  general  geology  and  copper 
prospects.  Their  report  is  accompanied  by  a geologic  map  of  the 
sound. 

MofRt  in  1907  obtained  information  concerning  the  progress  of 
copper  mining  and  prospecting,®  and  since  this  report  was  written 
Lincoln  has  described  the  Bonanza  mine  on  Latouche  Island.<^ 

THE  PRESENT  REPORT. 

The  senior  author,  assisted  by  Sidney  Paige,  made  a reconnaissance 
of  the  general  geology  and  mineral  resources  of  Prince  William 
Sound  in  1905,  and  this  work  was  continued  by  both  authors  of  this 
report  during  a few  weeks  in  the  summer  of  1908.  and  they  obtained 
some  additional  information  in  June,  1909.  Preliminary  reports  of 
this  work  have  already  been  published.®  In  this  reconnaissance 
practically  all  the  shores  of  the  sound  were  visited  with  the  excep- 
tion of  (1)  Montague  and  Green  islands,  (2)  the  outer  parts  of 
Hawkins  and  Hinchinbrook  islands,  and  (3)  some  of  the  islands  in 
the  northwestern  portion  of  the  sound.  A large  number  of  copper 
prospects  were  examined — in  fact,  all  the  important  prospects  and 
nearly  all  the  others. 

The  map  of  the  sound  (PI.  II)  which  accompanies  this  report  is 
based  on  the  charts  of  the  United  States  Coast  and  Geodetic  Survey, 
and  the  shores,  where  indicated  by  solid  lines,  are  taken  from  the 
detailed  surveys  of  that  organization  and  from  field  traverses  by  the 
authors.  Where  no  detailed  information  is  available  the  shores  are 
shown  by  broken  lines.  The  authors’  traverses  include  Port  Fidalgo, 
Port  Gravina,  and  practically  all  of  the  northern  and  western  shores 
of  the  sound  and  most  of  the  adjacent  islands. 

In  the  work  on  Prince  William  Sound  the  Survey  parties  received 
very  essential  aid  from  mining  men  and  prospectors  and  were  given 
free  access  to  all  mines  and  prospects  except  one.  The  cordial  cooper- 
ation of  the  people  of  the  sound  was  of  much  help.  Especial  thanks 
are  due  to  Capt.  J.  J.  Betties,  of  Valdez,  whose  intimate  knowledge 
of  the  sound  was  of  great  assistance  during  each  field  season. 

“ Emerson,  B.  K.,  Palache,  Charles,  and  Ulrich,  E.  O.,  Harriman  Alaska  Expedition, 
vol.  4,  1904. 

''  Schrader,  F.  C.,  and  Spencer,  A.  C.,  The  geology  and  mineral  resources  of  a portion 
of  the  Copper  River  district,  Alaska,  a special  publication  of  the  U.  S.  Geol.  Survey,  1901. 

Moffit,  F.  II.,  Notes  on  copper  prospects  of  Prince  William  Sound  : Bull.  U.  S.  Geol. 
Survey  No.  PA5,  1908,  pp.  176-178. 

''  Lincoln,  F.  C.,  The  Big  Bonanza  copper  mine  of  Latouche  Island,  Alaska : Econ. 
Geology,  vol.  4,  1909,  pp.  201-21.3. 

® Grant,  U.  S.,  Chopper  and  other  mineral  resources  of  Prince  William  Sound  : Bull.  U.  S. 
Geol.  Survey  No.  284,  1906,  pp.  78-87.  Grant,  U.  S.,  and  Higgins,  D .F.,  Copper  mining 
and  prospecting  on  Prince  William  Sound,  Alaska,  1908;  Bull.  U.  S.  Geol.  Survey  No.  379, 
1909,  pp.  87—96.  Grant,  U.  S.,  Gold  on  Prince  William  Sound,  Alaska  : Idem,  p.  97. 


14  KECONNAISSANCE  OF  PRINCE  WILLIAM  SOUND,  ALASKA. 

TOPOGRAPHY. 

MOUNTAINS  AND  PENEPLAIN. 

As  the  St.  Elias  Eange  extends  northwestward  from  Mount  St. 
Elias  it  divides  into  subordinate  ranges,  the  southern  one  of  which  is 
called  the  Chugach  Mountains.  West  of  Copper  Eiver  the  axis  of 
the  Chugach  Mountains  trends  a little  north  of  west,  runs  roughly 
parallel  with  the  northern  shore  of  Prince  William  Sound,  and  then 
bends  suddenly  to  the  southwest  and  forms  the  backbone  of  Kenai 
Peninsula.  The  continuation  of  the  same  mountains  to  the  south- 
west is  indicated  by  a few  small  islands  in  the  entrance  to  Cook  Inlet, 
and  the  mountains  themselves  reappear  on  Afognak  and  Kodiak 
islands.  The  Chugach  Mountains  nearly  surround  Prince  William 
Sound.  In  fact,  the  sound  lies  in  this  mountain  range,  but  to  the 
south  of  its  main  axis.  The  sound  is  thus  a highly  eroded  part  of 
the  Chugach  Mountains  into  which  the  sea  has  come. 

On  the  south  the  altitude  of  the  mountain  tops  is  much  lower  than 
on  the  north  and  northwest,  where  the  highest  peaks  occur  along  the 
axis  of  the  range.  About  Cordova  the  mountains  are  2,000  to  2,500 
feet  above  sea  level ; north  of  Cordova  Bay  they  rise  to  8,500  feet  or 
higher.  (See  PI.  III.)  On  Elrington  and  Latouche  islands,  at  the 
southwestern  entrance  to  the  sound,  the  mountains  rise  to  about  the 
same  altitudes  (1,500  to  2,000  feet),  but'  they  are  higher  at  inter- 
mediate points — for  example,  on  Montague  Island.  The  general 
altitude  of  the  mountains  on  this  island  is  probably  3,500  to  4,500 
feet,  but  accurate  figures  are  not  available.  North  of  Fidalgo  Bay 
the  general  height  of  the  mountain  tops  is  2,500  to  3,000  feet;  two 
peaks  here  which  rise  higher  than  the  others  are  Copper  Mountain, 
3,830  feet,  and  Mount  Denson,  5,886  feet.  South  of  Port  Valdez 
heights  of  3,500  to  4,500  feet  are  common,  and  north  of  Port  Valdez 
altitudes  of  4,500  to  6,000  feet  are  reached.  Still  farther  north,  along 
the  main  axis  of  the  range,  elevations  of  over  7,000  feet  are  reported. 
Still  higher  peaks  along  this  axis  are  known;  one  about  30  miles 
north  of  the  tide-water  terminus  of  the  Columbia  Glacier  rises  to 
11,100  feet,  and  three  peaks  which  are  7,500  to  8,200  feet  in  height 
occur  between  the  heads  of  Harriman  Fiord  and  Passage  Canal  of 
Prince  William  Sound  and  Turnagain  Arm  of  Cook  Inlet.  A peak 
near  the  west  side  of  College  Fiord  is  8,046  feet  in  height;  two  others, 
a few  miles  north  of  Harriman  Fiord,  rise  to  approximately  10,000 
feet,  and  north  of  these  two  is  at  least  one  still  higher  penk. 

Viewed  from  the  water  near  their  bases  these  mountains  appear 
very  irregular  in  altitude,  but  when  seen  from  some  high  peak  or 
from  a distance  of  10  miles  or  more  across  the  Avater  the  mountain 
tops  appear  to  rise  to  the  same  general  altitude.  The  fairly  accord- 
ant tops  of  these  mountains  composed  of  highly  folded  strata  thus 


GEOLOGICAL  SURVEY  BULLETIN  443  PLATE  III 


VIEW  LOOKING  NORTHWARD  FROM  VICINITY  OF  CORDOVA. 


TOP()(iIlAPHY. 


15 


suggest  an  ancient  peneplain  which  has  been  raised  far  al)ove  sea 
level,  warped,  and  highly  eroded.  This  erosion  has  been  so  complete 
that  no  extensive  remnants  of  the  old  peneplain  appear  about  Prince 
William  Sound,  and  in  places,  especially  in  the  central  part  of  the 
sound,  all  traces  of  this  old  surface  have  disappeared.  The  Avarping 
brought  up  the  peneplain  to  its  highest  point  along  the  axis  of  the 
Chugach  Mountains,  from  which  the  old  plain  slopes  southward 
toward  the  sea.  Minor  slopes  descend  from  the  east  and  the  west 
toward  the  center  of  the  sound. 

These  accordant  mountain  tops  can  be  seen  to  the  north  of  Orca 
Bay,  when  viewed  from  elevations  near  Cordova.  (See  PI.  III.) 
They  are  also  fairly  well  developed  on  Hinchinbrook  Island,  and  are 
especially  marked  on  Montague  Island  when  viewed  from  the  north- 
ern part  of  Latouche  Island  or  from  the  vicinity  of  Point  Countess, 
about  20  miles  northwest  of  Montague  Island.  On  the  west  side  of 
Port  Bainbridge  the  mountains  on  the  north  rise  to  about  3,000  feet 
and  becopie  lower  on  the  south  toward  Point  Puget,  near  which  they 
are  about  2,000  feet  above  sea  level. 

VALLEYS  AND  LOWLANDS. 

GENERAL  DESCRIPTION. 

The  topography  of  Prince  William  Sound  is  that  of  a maturely 
eroded  mountainous  district  with  the  forms  of  river  erosion  modified 
by  ice  erosion.  Into  such  a district  the  sea  has  come,  filling  the  main 
basin  of  the  sound  and  extending  far  up  the  valleys  that  lead  into  it. 
The  main  valleys  when  the  district  was  all  above  sea  level  probably 
ran  southward,  possibly  one  to  the  east  and  another  to  the  west  of 
Montague  Island,  while  tributary  streams  came  in  from  the  north- 
west and  northeast. 

Many  of  the  valleys  as  they  exist  to-day  are  of  the  fiord  type,  espe- 
cially in  the  northern  and  northwestern  parts  of  the  sound,  the  fiord 
character  not  being  so  prominent  in  the  eastern  part.  Among  the 
fiords  may  be  mentioned  Port  Valdez  and  Port  Wells,  the  latter  with 
two  fiord  arms.  The  main  stretch  of  Port  Valdez  is  about  14  miles  in 
length  and  3 miles  in  width.  Its  depth  is  from  000  to  more  than  800 
feet.  Soundings  in  Port  Wells  are  not  available.  The  deepest 
known  part  of  the  sound  stretches  north-northeast,  between  Knight 
and  Chenega  islands,  from  Point  Countess  toward  the  entrance  to 
Unakwik  Inlet.  In  this  stretch  are  soundings  of  more  than  1,800  feet, 
and  just  east  of  Long  Island  one  of  2,460  feet  has  been  made. 

The  relation  of  some  of  the  valleys  to  geologic  structure  is 
marked.  The  axis  of  Port  Valdez  practically  coincides  with  the 
strike  of  the  graywackes  and  slates  along  its  sides,  and  the  depression 
in  which  this  fiord  lies  is  probably  cut  in  the  more  easily  eroded  slates. 

58668°— Bull.  443— 10 2 


16  KECONNATSSANCE  OF  PRINCE  WILLIAM  SOUND,  ALASKA. 

The  main  body  of  Jackpot  Bay,  west  of  Chenega  Island,  has  cliffs  of 
resistant  graywackes  along  its  sides,  but  the  axis  of  the  bay  shows  out- 
crops of  softer  slates,  to  which  the  location  of  the  bay  is  undoubtedly 
due.  The  southeastern  arm  of  Port  Nellie  Juan  is  also  parallel  to 
the  strike  of  the  surrounding  rocks.  Tatillek  Narrows,  between  Bligh 
Island  and  Ellamar,  lies  in  an  easily  eroded  belt  of  black  slates,  and 
the  long,  narrow  island  in  this  passage  is  composed  of  a more  resist- 
ant dike  of  diabase.  Latouche,  Elrington,  and  Hoodoo  islands  and 
the  passages  between  them  lie  along  the  general  strike  of  the  rocks  of 
these  islands.  It  is  quite  likely  that  the  long  axis  of  Montague  Island 
is  also  parallel  with  the  general  trend  of  the  rocks  composing  that 
island. 

The  most  marked  valley  in  this  region  is  that  which  extends  from 
the  head  of  College  Fiord  through  Port  Wells,  Cochrane  Bay,  and 
the  upper  stretch  of  Port  Nellie  Juan.  This  is  a distance  of  56  miles 
at  sea  level,  and  the  depression  is  continued  for  an  unknoAvn  distance 
to  the  northeast  in  the  valley  in  Avhich  lies  the  Harvard  Glacier, 
and  also  an  unknown  distance  to  the  southwest  of  the  head  of  Port 
Nellie  Juan. 

The  effect  of  faults  in  locating  depressions  is  not  so  evident,  as 
such  displacements  in  strata  of  uniform  lithology  are  not  easy  of 
determination.  The  axis  of  Jack  Bay,  however,  seems  to  have  been 
determined  by  a fault.  The  abrupt  change  in  direction  of  Port 
Valdez  at  its  west  end,  with  the  fact  that  high  mountains  occur 
directly  to  the  west  of  the  main  part  of  this  inlet,  perhaps  indicates 
a fault;  and  it  is  possible  that  the  inlet  itself  lies  in  a down-faulted 
block  or  graben,  but  the  evidence  for  this,  aside  from  the  topography, 
is  not  at  hand.  The  straight  and  deep  channel  which  runs  southeast- 
ward from  the  mouth  of  Icy  Bay  and  cuts  in  a nearly  straight  line 
across  Point  Countess  and  the  northeast  ends  of  Bainbridge,  Fleming, 
Hoodoo,  and  Latouche  islands  suggests  a down-faulted  block. 

At  a number  of  places  in  the  eastern  part  of  Prince  William  Sound 
there  are  fairly  flat,  low-lying  islands,  forelands,  and  vallej'^s  from 
which  the  mountains  as  a rule  rise  steeply.  These  flats  are  regarded 
as  parts  of  an  erosional  surface  which  was  developed  not  far  above 
the  present  sea  level.  In  height  this  surface  is  commonly  20  to  60  feet 
above  tide,  and  there  are  a considerable  number  of  areas  which  do  not 
exceed  100  feet  in  altitude.  Islands  of  this  character,  which  have 
remarkably  level  surfaces,  occur  close  to  Rocky  Point  near  the  en- 
trance to  Galena  Bay ; and  the  Porpoise  Rocks,  near  Nuchek,  at  the 
west  end  of  Hinchinbrook  Island,  are  also  of  this  nature.  The  islands 
north  and  west  of  Bligh  Island  are  likewise  low.  The  lowland  about 
the  village  of  Tatitlek,  south  of  Ellamar,  belongs  with  this  plain,  as 
do  also  the  forelands  of  Sheep  and  Bomb  points,  on  the  north  side  of 
Cordova  Bay,  and  parts  of  the  north  side  of  Hinchinbrook  Island. 


LOWLAND  PLAIN  BETWEEN  LANDLOCKED  AND  FIDALGO  BAYS, 

Looking  toward  Bowie  Bay  from  the  south  slope  of  Copper  Mountain.  Photograph  by  Cantwell. 


TOPOGRAPHY. 


17 


One  of  the  most  characteristic  forelands  is  the  end  of  the  point  sej)- 
arating  Landlocked  and  Fidalgo  bays.  This  is  shown  in  Plate  IV. 
Among  the  valleys  whose  floors  probably  belong  to  this  same  plain  is 
that  extending  from  Boulder  Bay  northward  to  Galena  Bay,  also  the 
valley  running  southward  from  Snug  Corner  Cove  toward  Knowles 
Head  and  the  two  valleys  running  southward  from  Bowie  Bay. 

This  flat  surface  was  examined  in  two  places,  one  near  Rocky  Point 
and  the  other  just  east  of  Nuchek.  The  upturned  strata  were  found 
to  be  beveled  across  by  the  plain,  and  the  surface  of  the  rocks  was,  in 
places,  striated  and  covered  by  till.  These  features  are  probably  also 
characteristic  of  the  lowlands  where  not  examined  in  detail.  The 
plain,  then,  is  clearly  earlier  than  the  last  glaciation  of  the  district 
and  is  thought  to  be  a partial  peneplain  which  has  later  been 
smoothed  over  by  glacial  ice.  Some  parts  of  the  plain,  especially  the 
islands  and  the  forelands,  may  have  been  cut  by  wave  erosion,  but 
this  would  not  be  the  case  for  the  valleys  and  for  some  protected 
points.  - This  plain  was  noted  by  Schrader  and  Spencer,®  and  a sim- 
ilar plain  has  been  described  by  Gilbert  ^ in  southeastern  Alaska. 

RECENT  CHANGES  OF  LEVEL. 

This  lowland  surface  was  not  noted  on  the  west  side  of  Prince 
William  Sound.  If  it  exists  there  it  is  now  probably  below  sea  level. 
In  fact,  there  is  evidence  pointing  to  the  recent  depression  of  the 
shore  line  in  certain  places  in  the  western  part  of  the  sound.  At  one 
point  on  the  east  shore  of  Knight  Island  tundra  with  tree  roots  was 
found  covered  by  all  but  the  lowest  tides.  On  the  south  side  of  the 
same  island,  about  a mile  west  of  Point  Helen,  is  a storm  beach  built 
across  the  mouth  of  a small  cove  and  in  this  cove  the  high  tide  runs 
up  among  the  trees  and  has  killed  large  numbers  of  them.  A similar 
phenomenon,  but  less  marked,  is  seen -in  a small  cove  on  the  west  side 
of  Latouche  Island,  three-fourths  of  a mile  southwest  of  Horseshoe 
Bay.  The  shallow  water  known  as  Dangerous  Passage,  between 
Chenega  Island  and  the  mainland,  is  possibly  due  to  the  recent 
depression  of  the  lowland  surface  already  described. 

On  Port  Gravina  and  between  Sheep  and  Simpson  bays  there  has 
been  a very  noticeable  recent  depression  of  the  shore  line.  At  the  lat- 
ter locality,  near  the  head  of  a small  cove,  the  tundra  extends  below 
high  tide,  and  in  this  tundra  are  dead  trees  whose  roots  are  covered 
at  high  tide.  There  has  been  a depression  of  at  least  4 feet,  and  prob- 
ably more,  at  this  locality.  On  the  southeast  side  of  Port  Gravina 

“ Schrader,  F.  C.,  and  Spencer,  A.  C.,  The  geology  and  mineral  resources  of  a portion  of 
the  Copper  River  district,  Alaska,  a special  publication  of  the  U.  S.  Geol.  Survey,  1901, 
pp.  75-76. 

Gilbert,  G.  K.,  Harriman  Alaska  Expedition,  vol,  3,  1904,  pp.  130-134. 


18  RECONNAISSANCE  OF  PRINCE  WILLIAM  SOUND,  ALASKA. 

tliere  are  large  numbers  of  dead  trees  killed  by  the  high  tides,  and 
near  the  head  of  a small  bay  opposite  the  native  settlement  (Parsha’s) 
tundra  holding  tree  roots  is  being  cut  into  by  the  waves  and  extends 
down  almost  to  low  tide,  this  indicating  a depression  of  at  least  10 
feet. 

At  certain  points  on  the  sound  there  has  been  a recent  elevation  of 
the  shore  line.  One  such  locality  is  Columbia  Bay,  on  which  old 
beach  lines,  3 to  5 feet  above  present  high  tide,  occur  at  several  places, 
especially  in  a small  bay  on  the  east  side  of  and  1 mile  northeast  of 
the  eastern  entrance  to  Columbia  Bay.  Here  there  is  a platform,  5 
feet  above  present  high  tide,  with  a small  sea  cliff  at  the  landward 
side.  On  this  platform  are  still  standing  dead  trees  a foot  in  diameter, 
and  with  these  is  a live  spruce  4 inches  in  diameter,  which  has  grown 
since  the  platform  Avas  elevated  above  sea  level.  About  6 inches  of 
tundra  has  formed  on  this  platform  and  is  now  being  cut  into  by  the 
])resent  waves,  thus  indicating  at  least  a slight  depression  since  the 
period  of  elevation.  Plate  VI,  shows  this  elevated  beach. 

GLACIATION. 

All  about  Prince  William  Sound  are  striking  evidences  of  glacia- 
tion. Smoothed  and  striated  rock  surfaces,  roches  moutonnees,  hang- 
ing valleys,  U-shaped  valleys,  fiords,  etc.,  are  seen  everywhere  except 
in  parts  of  the  higher  mountains.  Extensive  deposits  of  till  and 
glacial  gravels  are  not  common,  the  district  being  one  of  glacial  ero- 
sion rather  than  of  glacial  deposition.  The  glaciated  surfaces,  Avhile 
smooth  in  detail,  are  commonly  very  irregular.  This  is  especially 
the  case  where  underlying  rocks  are  surface  greenstones,  a terrane 
which  gives  rise  to  irregular  shore  lines  and  diversified  topography. 
On  Knight  Island,  which  is  made  up  mainly  of  these  greenstones,  this 
irregularity  of  shore  line  and  of  surface  is  marked,  and  Plate  VI,  A, 
shows  such  a typical  surface  as  well  as  the  irregular  fiord-like  charac- 
ter of  the  shore. 

EARLY  GLACIATION. 

During  comparatively  recent  geologic  time,  the  Pleistocene  or  even 
later  (for  evidences  of  this  glaciation  are  exceedingly  fresh,  having 
hardly  been  touched  by  erosion  in  this  district  of  heavy  rainfall),  an 
extensive  ice  sheet  covered  the  district  embracing  Prince  William 
Sound.  The  ice  filled  in  all  of  the  sound  and  rose  high  up  on  the 
fianks  of  the  mountains.  The  direction  of  movement  of  this  ice  sheet 
Avas  toAvard.the  south  or  soutliAvest,  but  much  evidence  of  this  moA^e- 
ment  Avas  obliterated  in  the  later  stages  of  glaciation  by  ice  tongues 
moving  doAvn  the  valleys,  and  the  stria'  seen  to-day  are  in  the  main 
those  made  by  these  local  tongues  of  ice.  The  edge  of  the  ice  sheet 
probably  aa  as  bordered  by  the  sea  out  beyond  the  present  shore  line, 


BULLETIN  443  PLATE 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  443  PLATE  VI 


A.  GLACIATED  MOUNTAINS  AND  FIORDS,  NORTH  END  OF  KNIGHT  ISLAND. 

Looking  north  along  Louis  Bay.  The  topography  is  typical  for  districts  underlain  by  greenstones  of 

the  Orca  group. 


B.  ELEVATED  BEACH,  GLACIER  BAY. 


TOPOGRAPHY. 


19 


for  the  mountains  at  the  south  end  of  Elrington  Island  and  those  on 
Hinchinbrook  Island  are  rounded  by  glaciation.  The  outer  side  of 
Montague  Island  has  not  been  examined,  but  it  is  very  probable  that 
this  also  has  been  glaciated. 

The  height  to  which  the  ice  rose  above  the  present  sea  level  varies 
somewhat,  increasing  toward  the  north.  About  Orca  this  smoothing 
of  topograph}^  goes  up  to  2.300  feet,  and  north  of  Cordova  Bay  it 
reaches  2,500  feet.  (See  PI.  III.)  Just  northeast  of  Ellamar  is  a 
mountain  whose  peaks,  from  north  to  south,  are  respectively  1,010, 
2,008,  3,044,  2,008,  2,145,  and  2,005  feet  in  height.  All  these  peaks 
are  rounded  by  glaciation  except  the  highest,  the  upper  200  feet  of 
which  was  possibly  not  glaciated.  (See  PI.  X,  A.)  On  the  south 
side  of  Port  Valdez  glaciation  extends  up  to  about  3,200  feet.  On 
the  west  side  of  the  sound  the  limit  of  glaciation  is  a little  lower  than 
on  the  east  side  as  noted  above.  About  Port  Bainbridge  the  rounded 
slopes  extend  up  to  approximately  2,000  feet.  On  Elrington  and 
Latouche  islands  the  peaks  rise  to  over  2,000  feet  and  are  glaciated 
nearly  or  quite  to  their  summits.  Among  the  highest  peaks  on 
Knight  Island  are  three  known  as  the  Three  Giants,  just  south  of  the 
extreme  east  end  of  Drier  Bay.  The  tops  of  these  peaks  are  sharp 
and  not  glaciated ; the  smoothing  by  the  ice  extends  up  to  about  2,400 
feet.  (See  PI.  V.) 

After  the  main  ice  sheet  became  much  reduced  in  size  local  glaciers 
did  much  to  continue  the  work  of  glacial  erosion,  and  practically  all 
the  valleys  reaching  into  the  sound  carried  glaciers.  There  was  at 
this  time  in  certain  jDlaces  active  cutting  back  of  cirque  heads  and 
consequent  sharpening  of  the  topography,  in  some  localities  below 
the  former  maximum  height  of  glaciation.  Such  cirque  action  was 
prominent  on  Latouche  Island,  on  whose  northwestern  slope  several 
well-marked  cirques  can  now  be  seen.  One  of  these  cirques  lies  just 
back  of  Horseshoe  Bay  and  another  just  back  of  Wilson  Bay.  (See 
PI.  XII.)  One  of  the  most  typical  cirques  is  near  the  south  end  of 
the  island,  southeast  of  Montgomery  Bay.  These  all  face  toward 
the  northwest. 

RECENT  GLACIATION. 

The  conditions  just  noted  above  gradually  changed  until  most  of 
the  valleys  became  free  of  ice  and  present  conditions  were  established. 
There  are  now  a large  number  of  alpine  glaciers  about  the  shores  of 
the  sound  and  on  Montague  Island.  Most  of  these  glaciers  do  not 
reach  sea  level,  but  about  the  north  and  west  shores  of  the  sound 
there  are  still  several  extensive  ice  fields,  from  which  ice  tongues  move 
down  to  sea  level.  The  locations  of  these  are  shown  on  Plate  II. 
The  most  numerous  glaciers  are  about  the  two  arms  of  Port  Wells — 
College  and  Harriman  fiords— and  the  largest  glacier  on  the  sound 


20  RECONNAISSANCE  OF  PRINCE  WILLIAM  SOUND,  ALASKA. 

is  the  Columbia,  at  the  head  of  Columbia  Bay.  This  magnificent 
glacier  has  a semicircular  front  of  about  4 miles,  most  of  which  is 
along  tide  water.  About  24  miles  of  this  front  is  a nearly  vertical  ice 
clilf  approximately  400  feet  in  height.® 

GENERAL  GEOLOGY. 

INTRODUCTION. 

Tlie  rocks  of  Prince  William  Sound  are  readily  separable  into 
those  of  sedimentary  and  those  of  igneous  origin.  To  the  igneous 
division  belong  (1)  granites,  (2)  acidic  dike  rocks,  (3)  basic  intrusive 
rocks,  and  (4)  basic  surface  flows.  The  granites,  which  are  mainly 
biotite  granites,  occur  in  several  masses,  the  largest  of  which  is  that 
of  Esther  Island.  They  are  intrusive  into  the  surrounding  rocks, 
which  they  have  metamorjihosed  much  less  than  is  customary  in 
areas  of  granitic  intrusions.  The  granites  are  of  later  date  than 
the  Valdez  group  and  are,  in  one  case  at  least — that  of  the  Sheep  Bay 
granite — later  than  the  Orca  group.  The  acidic  dikes  are  mainly 
aplitic  in  character,  are  not  numerous,  and  are  of  small  size.  Dikes 
of  quartz  porphyry  are  known  at  two  localities,  on  Unakwik  Inlet  and 
in  the  nunatak  of  the  Columbia  Glacier.  The  aplite  dikes  cut  the 
Valdez  group  and  the  quartz  porphyry  is  perhaps  later  than  the 
Orca.  The  basic  intrusives  are  diabases,  gabbros,  and  diorites;  some 
of  these  are  intrusive  into  the  Orca  rocks.  Gabbro  occurs  in  small 
amount  and  is  known  at  two  localities,  on  the  northeast  end  of 
Latouche  Island,  where  it  intrudes  the  Orca  sediments,  and  on  Esther 
Island,  where  it  is  associated  with  granite.  Diorite  occurs  as  a phase 
of  some  of  the  granites,  especially  that  on  Culross  Passage.  Dioritic 
rocks  also  occur  as  alteration  phases  of  diabase  and  gabbro.  The 
basic  flows  are  commonly  altered  green  igneous  rocks,  and  are  con- 
veniently grouped  under  the  name  of  greenstone.  They  are  in  many 
places  ellipsoidal  in  character;  that  is,  they  consist  largely  of  more 
or  less  spherical  masses  which  vary  from  a few  inches  to  10  feet  in 
diameter.  (See  PI.  VIII.)  With  these  flows  are  dikes  and  also  sills, 
but  they  are  subordinate  in  amount  and  are  not  always  easily  recog- 
nized. The  basic  flows  belong  to  the  lower  part  of  the  Orca  group 
and  are  so  intimately  interstratified  ivith  the  sediments  of  that  age 
that  they  may  readily  be  considered,  in  structural  discussions,  as  a 
]iart  of  that  group. 

The  sedimentary  rocks  of  the  sound  show  marked  uniformity  in 
‘lithology.  They  are  mainly  slates,  gray  to  black  in  color,  and  gray- 
wackes.  The  latter  term  is  used  to  include  sediments  of  coarser  grain 

“ Some  of  the  glaciers  of  Prince  William  Sound  have  been  described  by  G.  K.  Gilbert 
(Ilarriman  Alaska  Expedition,  vol.  3,  1904,  pp.  71-97).  The  present  authors  expect  to 
submit  a separate  paper  dealing  with  these  glaciers. 


GENERAL  GEOLOGY. 


21 


than  the  slates,  which  closely  resemble  each  other.  The  rocks  vary, 
however,  from  graywackes  to  arkoses  and  even  to  sandstones  and 
quartzites,  but  the  term  graywacke  conveniently  covers  the  whole. 
The  sedimentary  rocks  are  essentially  without  fossils  and  are  in  gen- 
eral closely  folded,  but  not  highly  metamorphosed.  The  slates  and 
graywackes  alternate  in  thin  beds,  as  shown  in  Plate  VII,  J.,  and 
such  exposures  are  common  over  long  distances.  There  is  in  much 
of  the  region  no  segregation  of  these  rocks  into  a graywacke  and  a 
slate  division.  An  exception  to  this  statement  should  be  made  for 
parts  of  the  western  shores  of  the  sound,  where  the  rocks  are  mainly 
graywackes,  with  only  very  subordinate  amounts  of  slate. 

Because  of  the  uniform  lithology  of  the  sedimentary  rocks  of  the ' 
sound,  and  because  of  their  close  folding  and  lack  of  fossils,  it  has 
been  difficult  to  separate  these  rocks  into  different  formations  or  even 
into  different  groups.  Such  results  can  be  accomplished  only  by 
detailed  mapping,  which  is  not  possible  in  a reconnaissance  survey. 
The  results  here  presented  should  therefore  be  regarded  as  partly 
tentative,  and  the  mapping  is  also  of  that  nature.  That  the  sedimen- 
tary rocks  of  Prince  William  Sound  are  separable,  however,  into  two 
unconformable  series  is  clear.  That  there  are  more  than  two  series 
is  possible,  but  the  evidence  on  this  point  is  elusive.  The  two  divi- 
sions of  the  sedimentary  rocks  of  the  sound  are  the  Valdez  and  the 
Orca  groups,  the  latter  lying  unconformably  on  the  former.  At  the 
base  of  the  Orca  there  is  locally  a conglomerate  of  well-worn  pebbles, 
which  are  in  some  localities  graywacke  and  slate  set  in  a matrix  of 
graywacke ; with  the  conglomerate  are  bands  of  graywacke  and  slate 
closely  similar  to  the  rocks  which  form  the  pebbles.  In  such  localities 
only  the  most  detailed  work  can  surely  determine  to  which  formation 
certain  beds  belong. 

The  main  structural  and  historical  features  of  the  district  may  be 
briefly  outlined.  The  Valdez  rocks  are  the  oldest.  Their  base  and  the 
rocks  on  which  they  lie  have  not  been  recognized  in  this  region. 
The  Valdez  rocks  were  elevated,  folded,  eroded,  and  depressed  before 
the  deposition  of  the  Orca  rocks.  It  is  probable  that  during  the  Orca 
deposition  the  land  area  from  which  the  sediments  were  derived 
stood  to  the  north,  and  that  the  coast  line  was  much  farther  toward 
the  axis  of  the  Chugach  Range  than  at  present.  Later  more  folding 
took  place,  accompanied  by  elevation  of  the  Chugach  Mountains, 
which  now  sweep  into  a broad  curve  about  the  north  and  west  sides 
of  the  sound.  In  this  period  of  folding  and  elevation  the  sound  dis- 
trict had  impressed  upon  it  a broad  synclinal  structure,  and  the  later 
erosion  left  the  young  rocks  in  the  center  of  the  district  and  the  older 
rocks  on  the  outside — that  is,  to  the  north  and  west.  It  is  probable 
that  this  synclinal  structure  became  more  pronounced  by  further 
sinking  of  the  land,  which  brought  the  ocean  into  the  sound.  This 


22  RECONNAISSANCE  OF  PRINCE  WILLIAM  SOUND,  ALASKA. 

belted  arrangement  of  the  two  groups  of  rocks  is  evident  from  an 
inspection  of  the  geologic  map  (PL  II). 

SEDIMENTARY  ROCKS. 

VALDEZ  GROUP. 

GENERAL  DESCRIPTION. 

The  Valdez  group  was  named  by  Schrader, who  studied  these 
rocks  about  Port  Valdez  and  to  the  north  and  east.  Lithologically 
the  group  consists  of  slates  and  graywackes,  commonly  in  narrow 
alternating  bands.  These  rocks  have  been  partly  recrystallized  and 
in  places  should  be  called  schists,  but,  except  for  those  in  the  im- 
mediate neighborhood  of  the  intrusive  masses,  the  terms  graywacke 
and  slate  give  a more  accurate  idea  of  the  general  character  of  these 
rocks.  The  graywackes  still  show  their  original  angular  grains,  but 
the  cement  in  which  these  grains  lie  has  usually  been  recrystallized 
to  a mass  of  fine-grained  muscovite,  chlorite,  and  quartz,  and  the 
whole  rock  has  been  rendered  somewhat  schistose.  The  slates  vary 
from  black,  apparently  carbonaceous  rocks  to  those  which  are  gray 
in  color.  As  a rule  they  do  not  show  the  perfect  cleavage  of  roofing 
slates,  and  in  places  they  have  macroscopic  muscovite  scales.  These 
are  the  characters  of  the  Valdez  rocks  about  Port  Valdez,  their  type 
locality.  On  the  north  and  west  sides  of  the  sound  they  are  less 
metamorphosed  and  consist  in  large  part  of  massive  graywackes. 
Stretched  conglomerates  were  noted  in  this  group  by  Schrader.®  In 
the  vicinity  of  granitic  intrusive  rocks  biotite  has  been  extensively  de- 
veloped in  the  slates  and  graywackes  and  in  a few  places  nodular 
schists,  or  knotenschiefer,”  occur.  No  contemporaneous  igneous 
rocks  have  been  found  in  the  Valdez  group,  but  a few  green  schistose 
bands  in  the  slates  on  the  south  side  of  Port  Valdez,  a mile  and  a 
half  west  of  Fort  Liscum,  resemble  fine  water-laid  tuffs. 

North  of  Port  Valdez  this  group  of  rocks  extends  to  the  northern 
shores  of  Lake  Klutina,  a distance  of  some  50  miles.  On  the  east  they 
extend  to  Copper  River  and  up  that  stream  to  the  mouth  of  the 
Chitina.  South  of  the  entrance  to  Port  Valdez  the  Valdez  rocks 
occupy  the  shores  of  Jack  Bay  and  of  the  eastern  part  of  Galena  Bay, 
east  of  which  their  southern  limit  runs  north  of  Copper  Mountain. 
They  possibly  reach  Fidalgo  Bay,  but  from  present  knowledge  this 
bay  is  thought  more  probably  to  lie  in  the  Orca  group.  On  the  west 
side  of  Valdez  Narrows,  opposite  the  mouth  of  Jack  Bay,  the  Valdez 
rocks  are  replaced  for  several  miles  by  the  slates  and  greenstones  of 

" Schrader,  F.  C.,  A reconnaissance  of  a part  of  Prince  William  Sound  and  the  Copper 
River  district,  Alaska,  in  ISOS;  Twentieth  Ann.  Rept.  IT.  S.  Geol.  Survey,  pt.  7,  1900, 
p.  408. 


SEDIMENTARY  ROCKS. 


23‘ 


the  Orca  group,  but  the  older  group  reappears  northeast  of  Point 
Freemantle  and  from  this  point  westward  and  southward  to  Port 
Bainbridge  forms  with  some  granite  masses  the  main  shore  line  of 
the  sound. 

Structurally  the  Valdez  rocks  are  closely  folded,  the  closeness  of 
the  folds  and  the  metamorphism  of  the  rocks  increasing  to  the 
north  as  the  axis  of  the  Chugach  Range  is  approached.  On  the 
south  side  of  Port  Valdez  the  rocks  are  very  closely  folded  into 
a series  of  anticlines  and  synclines  which  are  overturned  to  the 
south,  thus  giving  monoclinal  dips  of  50°  to  70°  N.  The  cleavage 
along  the  south  shore  of  Port  Valdez  has  commonly  the  same  strike 
and  within  a few  degrees  of  the  same  dip  as  the  bedding.  On  the  north 
shore  of  Jack  Bay  the  rocks  are  thrown  into  close  folds,  overturned 
toward  the  south-southeast,  whose  axes  pitch  toward  the  west-south- 
west. On  the  south  side  of  the  bay  the  strike  is  west-northwest, 
practically  parallel  to  the  trend  of  the  axis  of  the  bay,  and  the  dip 
is  steeply  to  the  north.  This  relation  seems  to  be  due  to  a fault 
running  along  the  axis  of  the  bay,  and  a small  fault  parallel  to  this 
general  direction  has  been  noted  on  the  north  side  of  the  bay  just 
north  of  the  end  of  the  point  which  divides  the  bay  into  two  arms. 
The  continuation  of  this  fault  is  thought  to  account  for  the  bringing 
in  of  the  Orca  group  on  the  west  side  of  Valdez  Narrows;  at  this 
place  the  south  side  of  the  fault  is  the  downthrown  side. 

From  Point  Freemantle  westward  to  Esther  Island  the  rocks  along 
the  headlands  which  separate  the  indentations  in  the  coast  line  are, 
with  the  exception  of  granite,  graywackes,  and  slates.  These  are  in 
many  places  highly  brecciated. 

AGE  AND  CORRELATION. 

Fossils  have  been  found  in  the  Valdez  rocks  in  only  one  locality. 
This  occurrence  is  described  as  follows : ® 

Plant  remains,  consisting:,  according  to  Mr.  F.  H.  Knowlton,  of  bark  or 
stems,  were  collected  from  Point  Lowe,  in  the  southwest  part  of  Port  Valdez, 
bnt  nnfortm lately  were  without  character  and  too  greatly  altered  for  determina- 
tion. 

The  exact  age  of  the  Valdez  rocks  is  not  known.  They  have  been 
assigned  provisionally  to  several  horizons,  from  Silurian  to  Ter- 
tiary, in  the  geologic  column.^  From  their  investigations  in  the 

“ Schrader,  P.  C.,  A reconnaissance  of  a part  of  Prince  William  Sound  and  the  Copper 
River  district,  Alaska,  in  1898  : Twentieth  Ann.  Kept.  U.  S.  Geol.  Survey,  pt.  7,  1900, 
p.  409. 

Schrader,  F.  C.,  op.  cit,  p.  409.  Schrader,  P.  C.,  and  Spencer,  A.  C.,  The  geology  and 
mineral  resources  of  a portion  of  the  Copper  River  district,  Alaska,  a special  publication 
of  the  U.  S.  Geol.  Survey,  1901,  pp.  36-37.  Mendenhall,  W.  C.,  Geology  of  the  central 
Copper  River  region,  Alaska  : Prof.  Paper  IT.  S.  Geol.  Survey  No.  41,  1905,  pp.  32-33. 
Brooks,  A.  II.,  The  geography  and  geology  of  Alaska : Prof.  Paper  U.  S.  Geol.  Survey 
No.  45,  1906,  pp.  228-230. 


24  RECONNAISSANCE  OF  PRINCE  WILLIAM  SOUND,  ALASKA. 


Copper  River  region,  where  the  Valdez  rocks  appear  to  be  older 
than  limestone  and  greenstone  " assigned  to  the  Carboniferous,  Schra- 
der and  Spencer^  thought  that  the  Valdez  rocks  were  possibly  older 
than  the  Silurian.  The  Valdez  group  lies  unconformably  below  the 
Orca  group,  in  which  fossils  of  probable  Lower  Jurassic  age  have 
been  found.  Present  knowledge  indicates  the  probability  that  the 
Valdez  group  should  be  referred  to  the  Paleozoic,  but  its  exact 
horizon  in  that  era  is  unknown. 

The  relation  of  the  Valdez  group  to  the  Sunrise  “ series  ” has  also 
been  a matter  of  some  uncertaijity.  The  Sunrise  ‘‘  series  ” has  been 
described  by  Mendenhall,^  Moffit,^  and  Paige  and  Knopf.®  The  Sun- 
rise rocks  are  very  similar  in  lithology  to  those  of  the  Valdez  group, 
and  they  occur  in  typical  development  about  the  shores  of  Passage 
Canal,  in  the  northwestern  part  of  Prince  William  Sound.  They 
have  been  described  as  extending  from  this  place  westward  to 
Turnagain  Arm  of  Cook  Inlet,  northward  from  Turnagain  Arm 
to  Mataniiska  River,  and  southward  from  Turnagain  Arm  to  Resur- 
rection Bay,  thus  forming  the  eastern  and  central  parts  of  Kenai 
Peninsula.  As  a rule  the  Sunrise  rocks  are  a little  less  metamor- 
phosed than  the  Valdez  rocks  about  Port  Valdez,  but  no  break  has 
been  discovered  between  the  Sunrise  and  the  Valdez.  In  fact,  it 
appears  that  the  Valdez  rocks  on  Port  Valdez  can  be  traced  west- 
ward along  the  north  shore  of  Prince  William  Sound  to  Passage 
Canal,  the  type  locality  for  the  Sunrise  “ series.”  It  thus  seems  that 
the  Valdez  and  the  Sunrise,  as  first  described,  are  the  same;  and 
consequently  rocks  to  which  the  term  Sunrise  has  been  applied  about 
the  western  part  of  the  sound  are  here  mapped  as  Valdez.  The  pub- 
lished descriptions  of  the  Sunrise  “ series  ” mention  conglomerates, 
and  rocks  referred  to  the  Orca  group  f have  recently  been  discovered 
on  the  east  side  of  Resurrection  Bay.  , It  thus  seems  that  the  Sunrise 
“ series,”  though  in  the  main  equivalent  to  the  Valdez  group,  prob- 
ably contains  some  areas  of  Orca  age. 

•'  This  limestone  has  since  been  proved  to  he  of  Triassic  age,  hut  the  greenstone  may  be 
Carboniferous. 

**  Loc.  cit. 

Mendenhall,  W.  C.,  A reconnaissance  from  Resurrection  Bay  to  the  Tanana  River, 
Alaska,  in  1898  : Twentieth  Ann.  Rept.  U.  S.  Geol.  Survey,  pt.  7,  1900,  pp.  305-307. 

MofRt,  F.  H.,  Gold  fields  of  the  Turnagain  Arm  region  : Bull.  U.  S.  Geol.  Survey  No. 
277,  190G,  pp.  17-19. 

« Paige,  Sidney,  and  Knopf,  Adolph,  Geologic  reconnaissance  in  the  Matanuska  and 
Talkeetna  basins,  Alaska  : Bull.  LT.  S.  Geol.  Survey  No.  327,  1907,  pp.  12-16. 

f Grant,  U.  S.,  and  Higgins,  D.  F.,  Notes  on  the  geology  and  mineral  prospects  in  the 
vicinity  of  Seward,  Kenai  Peninsula  : Bull.  U.  S.  Geol.  Survey  No.  379,  1909,  pp.  98-107. 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  443  PLATE  VII 


A.  SLATE  AND  GRAYWACKE  OF  THE  ORCA  GROUP,  GULL  ISLAND. 
The  lighter-colored,  more  resistant  layers  are  graywacke. 


B.  SLATE  OF  THE  ORCA  GROUP  OVERLAIN  BY  GREENSTONE  NEAR  ROCKY  POINT. 
Fragments  of  slate  found  here  contained  worm  tubes  ( Terebellina  palacliei  Ulrich). 


SEDIMENTARY  ROCKS. 


25 


ORCA  GROUP. 

GENERAL  DESCRIPTION. 

The  Orca  group  was  named  by  Schrader  " in  1900,  and  was  later 
studied  by  Schrader  and  Spencer.^  Lithologically  the  Orca  group 
consists  of  graywackes,  slates,  and  greenstones,  with  subordinate 
amounts  of  conglomerates  and  limestones.  The  rocks  here  termed 
graywackes  vary  from  true  graywackes  to  arkoses  and  to  sandstones 
and  quartzites,  but  the  general  similarity  of  these  rocks  and  the  angu- 
lar nature  of  their  constituent  grains,  which  are  embedded  in  a sparse 
cement  or  matrix,  show  that  they  are  all  closely  allied  and  can  be 
grouped  for  convenience  of  description  under  one  name.  The  rapid 
alternation  of  bands  of  slate  and  graywacke  is  a characteristic  fea- 
ture of  many  outcrops  of  the  Orca  rocks.  (See  PL  VII,  A,)  The 
slates,  both  black  and  gray,  and  graywackes  are  found  very  abund- 
antly in  exposures  of  Orca  rocks.  Soft  black  slates  are  more  com- 
mon in  the  lower  part  of  the  formation  and  are  in  many  places 
associated  with  the  greenstones. 

Conglomerates  occur  in  a number  of  places,  especially  (1)  on  both 
sides  of  the  entrance  to  Galena  Bay,  (2)  on  the  north  shore  of  Fidalgo 
Bay  west  of  Fish  Bay,  (3)  on  the  north  shore  of  Orca  Bay  between 
Sheep  and  Simpson  bays,  (4)  on  the  northwest  side  of  Latouche 
Island  near  the  Bonanza  mine,  (5)  near  the  northeast  corner  of  Hoo- 
doo Island,  and  (6)  on  the  northwest  side  of  Elrington  Island.  The 
conglomerates  will  be  described  further  in  connection  with  the  special 
descriptions  of  the  Orca  group. 

Limestones  are  not  common.  They  occur  in  small  amount  (1) 
north  of  the  entrance  to  Galena  Bay  where  the  Orca  rocks  are  near 
to  the  Valdez,  (2)  just  north  of  Gravina  Point,  (3)  on  Cedar  Bay  on 
the  north  side  of  Hawkins  Island,  and  (4)  at  the  Banta  shaft  of  the 
Beynolds- Alaska  Development  Company  on  Latouche  Island.  At 
the  first-mentioned  locality  limestone,  or,  rather,  calcite,  occurs  as  a 
cement  to  some  of  the  coarse-grained  fragmental  rocks  at  the  base  of 
the  Orca  group.  At  the  second  locality  are  a few  low  exposures  of 
finely  banded,  highly  contorted,  fine-grained  siliceous  limestone,  which 
is  red,  gray,  and  green  in  color.  At  the  third  locality  the  limestone 

consists  of  layers  varying  from  1 to  2 feet  or  more  in  thickness.  It 
is  compact  or  dense  in  texture  and  dark  blue  or  black  in  color.” At 
the  fourth  locality  a number  of  blocks  of  coarse-grained  gray  lime- 

® Schrader,  F.  C.,  A reconnaissance  of  a part  of  Prince  William  Sound  and  the  Copper 
River  district,  Alaska,  in  1898  : Twentieth  Ann.  Rept.  U.  S.  Geol.  Survey,  pt.  7,  1900, 
pp.  404-408. 

^ Schrader,  P.  C.,  and  Spencer,  A.  C.,  The  geology  and  mineral  resources  of  a portion 
of  the  Copper  River  district,  Alaska,  a special  publication  of  the  U.  S.  Geol.  Survey, 
1901,  pp.  37-44. 

'■  Schrader,  F.  C,,  op.  cit.,  p,  406. 


26  RECONNAISSANCE  OF  PRINCE  WILLIAM  SOUND,  ALASKA, 

stone  Avere  found  on  the  dump  from  a shaft  about  100  feet  deep.  This 
limestone  probal)ly  came  from  a bed  near  the  bottom  of  the  shaft. 
The  rock  is  pcu’ous  and  contains  grains  of  quartz  and  flakes  of  miisco- 
Aute.  Some  black,  calcareous  bands  have  been  found  elseAAdiere  in  the 
slates  and  are  probably  more  common  than  the  field  notes  Avould 
indicate,  for  such  bands  are  easily  overlooked. 

The  greenstones  are  abundant  in  the  lower  part  of  the  Orca,  and 
their  distribution  is  shoAvn  on  the  geologic  map  (PI.  II).  They  are 
in  the  main  surface  floAvs,  interbedded  Avith  the  sediments.  One  veiw 
marked  characteristic  of  these  greenstones  is  their  ellipsoidal  char- 
acter. (See  PI.  VIII.) 

The  Orca  rocks  can  be  separated  into  two  divisions,  one  of  Avhich  is 
characterized  by  the  presence  of  much  greenstone  Avith  subordinate 
amounts  of  slates,  usually  black  in  color,  graywackes,  and  conglom- 
erates. The  other  division  has  little  or  no  greenstone,  and  consists  of 
slates  and  graywackes.  The  division  characterized  by  greenstone  lies 
next  to  the  Valdez  rocks  on  the  north  and  Avest  sides  of  the  sound, 
and  is  older  than  the  division  consisting  of  slates  and  graywackes — 
that  is,  the  early  part  of  the  Orca  was  a period  of  extrusion  of  many 
flows  of  basic  lava,  with  which  were  deposited  varying  amounts  of 
sediments.  The  main  volcanic  activity  seems  to  have  taken  place 
near  the  shore  line  of  the  Orca  Sea,  Avhile  farther  out  sediments  Avere 
being  deposited,  and  finally  sedimentation  became  the  prominent 
phenomenon  even  near  the  shore  line.  This  explanation,  together 
Avith  the  general  synclinal  structure  of  the  Orca  rocks,  Avill  account 
for  the  distribution  of  the  two  divisions  of  the  Orca  group  about  the 
sound.  (See  PI.  II.)  It  is  probable  that  Hawkins,  Hinchinbrook, 
and  Montague  islands  all  lie  in  the  upper  division  of  the  Orca,  but 
sufficient  information  is  not  at  hand  to  Avarrant  a positive  statement 
on  this  point. 

SPECIAL  DESCRIPTIONS. 

GALENA  EAA'. 

On  both  sides  of  the  entrance  to  Galena  Bay  there  are  extensive 
exposures  of  conglomerates,  greenstones,  and  black  slates,  Avith 
smaller  amounts  of  grayAvacke.  The  exposures  on  the  north  side  of 
the  entrance  are  of  special  interest  because  they  lie  near  the  junction 
of  the  Orca  and  Valdez  groups.  This  junction  line  runs  from  the 
shalloAV  bay  Avhich  is  about  a mile  north  of  the  entrance  to  Galena 
Bay  southeastward  nearly  to  the  mouth  of  the  stream  that  enters 
Galena  Bay  about  the  center  of  its  north  side.  To  the  north  and 
east  of  this  line,  as  exposed  along  the  shore,  are  slates  and  gray- 
wackes, with  no  observed  greenstones  except  some  small  dikes  in  one 
exposure.  These  slates  and  grayAvackes,  belonging  to  the  Valdez 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  443  PLATE  VIII 


A.  ELLIPSOIDAL  GREENSTONE  NEAR  ROCKY  POINT. 


B.  SECTIONS  ACROSS  ELLIPSOIDAL  GREENSTONE  NEAR  ROCKY  POINT. 


SEDIMENTAKY  HOCKS. 


27 


group,  arc  considerably  fractured  and  closely  fojded.  North  of  the 
above-mentioned  junction  line  the  slates  and  graywackes  strike  west- 
northwest,  with  dips  of  to  70°  NNE.  The  rocks  lie  in  closely 
compressed  folds,  overturned  to  the  sonth-southwest,  and  these  folds 
pitch  toward  the  west-northwest.  On  the  north  shore  of  Galena  Bay, 
east  of  the  junction  line,  the  direction  of  strike  is  not  constant  and 
the  dip  varies  from  55°  to  90°. 

On  the  south  and  west  of  this  junction  line  lie  the  rocks  of  the 
lower  part  of  the  Orca  group.  Instead  of  highly  folded  and  frac- 
tured slates  and  graywackes  there  are  gently  folded  (with  dips  of 
10°  to  30°)  greenstones,  conglomerates,  and  slates,  with  smaller 
amounts  of  graywacke. 

At  the  head  of  the  shallow  bay  (above  mentioned)  about  a mile 
north  of  the  entrance  to  Galena  Bay  are  extensive  exposures  of  a 
rock  which  consists  of  fragments  of  all  sizes,  up  to  those  a foot  in 
diameter,  embedded  in  a matrix  that  varies  from  a coarse  graywacke. 


SE 


9 100  zoo  300  400  500  Feet 

(A) 


0 25 50  100  Feet 

(B) 


Figure  1. — Interbedding  of  sediments  and  basic  lava  flows,  Orca  group.  A,  About  1 mile 
north  of  the  entrance  to  Galena  Bay  ; B,  south  side  of  Galena  Bay,  directly  south  of  A. 
a.  Conglomerate  and  breccia  ; h,  graywacke  ; c,  slate  ; d,  ellipsoidal  greenstone  ; e,  diabase. 

with  calcite  cement,  to  a fine  black  slate.  Bedding  is  not  prominent, 
but  there  are  some  bands  which  are  of  fine  grain  and  are  continuous 
for  a distance  of  30  feet.  These  dip  10°  N.  32°  W.  The  fragments 
in  this  matrix  consist,  at  the  north  end  of  the  exposures,  largely  of 
slates  and  graywackes  similar  to  those  seen  in  place  to  the  north. 
Toward  the  south  end  of  the  exposures  the  fragments  are  larger  and 
consist  mainly  of  fine-grained  gray  diabase,  snbporphyritic  diabase, 
and  basic  amygdaloids.  The  fragments  vary  from  angular  to  well 
rounded,  though  the  angular  and  snbangular  ones  are  more  common. 
The  rock  of  these  exposures  is  probably  to  be  explained  as  frag- 
mental volcanic  material  deposited  in  water  along  with  rapidly 
accumulating  coarse  sediments.  These  exposures  are  evidently  close 
to  the  base  of  the  Orca. 

On  the  south  and  southwest  sides  of  the  above-mentioned  bay  there 
is  a distance  of  some  500  feet  between  the  exposures  just  described 
and  the  next  exposures,  a series  of  interbedded  diabase  flows  and 


28*  RECONNAISSANCE  OF  PRINCE  WILLIAM  SOUND,  ALASKA. 

black  slates,  six  of  the  former  and  five  of  the  latter.  (See  fig.-l,  .4.) 
The  strike  here  is  N.  78°  E.  and  the  dip  25°  N.  To  the  west  there 
are  other  bands  of  slate  between  lava  flows,  and  a most  impressive 
exhibition  of  flows  of  ellipsoidal  greenstones.  (See  PI.  VIII.) 

Near  the  end  of  the  point  southwest  of  this  bay  are  other  exposures 
of  slate  and  greenstone,  at  one  of  which  worm  tubes  {Terebellina 
palackei  Ulrich)  were  found.  (See  PL  VII,  B.)  Farther  south,  on 
both  sides  of  Galena  Bay,  are  other  exposures  of  conglomerates,  slates, 
greenstones,  and  graywackes  intimately  interbedded  with  each  other. 
The  relations  of  the  sediments  and  the  ellipsoidal  greenstones  at  one 
of  these  places  is  shown  in  figure  1,  B. 

ELLAMAR  AND  BLIGH  ISLAND. 

Along  the  shore  line  from  Pocky  Point  to  a place  within  a mile  and 
a half  of  Ellamar  are  many  exposures  of  greenstones,  which  are  com- 
monly ellipsoidal,  and  of  black  slates  with  graywackes.  The  passage 
between  Ellamar  and  Bligh  Island,  known  _as  Tatitlek  Narrows,  lies 
in  an  easily  eroded  mass  of  closely  folded  black  slate.  This  rock 
appears  in  outcrops  on  both  sides  of  the  passage.  The  strike  is  in 
general  northwest  and  southeast.  The  long,  narrow  island  in  Tatit- 
lek Narrows  is  made  up  largely  of  a dike  of  coarse-grained  diabase. 
The  northeastern  lobe  of  Bligh  Island  is  composed  of  greenstones  and 
slates,  as  is  Busby  Island.  The  main  part  of  Bligh  Island  consists 
of  slates  and  graywackes.  These  rocks  lie  in  more  open  folds  than 
are  common  about  Prince  William  Sound.  The  axes  of  the  folds 
have  a general  northwest-southeast  trend. 

KNIGHT  ISLAND. 

The  southeastern  part  of  Knight  Island,  southeast  of  a line  run- 
ning from  the  entrance  to  Discovery  Bay  to  the  eastern  arm  of 
Mummy  Bay,  is  composed  of  slate  and  graywacke,  with  little  green- 
stone. The  rest  of  the  island  is  almost  entirely  of  greenstone. 
This  rock  is  ellipsoidal  in  many  places,  but  toward  the  center 
of  the  island  the  ellipsoidal  nature  is  not  so  evident  and  the  coun- 
try rock  is  largely  altered  diabase,  which  in  places  has  become  a 
greenstone  schist.  Near  the  head  of  the  southeastern  arm  of  Herring 
Ba}^,  Knight  Island,  and  also  near  the  head  of  the  eastern  arm 
of  this  same  bay  greenstone  occurs  in  three  distinct  phases  as  fol- 
lows: (1)  The  common  ellipsoidal  flows;  (2)  fairly  coarse  grained 
green  diabase  whose  augite  has  largely  changed  to  hornblende;  (3) 
fine-grained,  dark,  almost  black,  fresh  diabase  cutting  the  other  rocks 
in  small  dikes.  About  a mile  east  of  Mallard  Bay,  one  of  the  south- 
ern arms  of  Drier  Bay,  the  greenstone  is  schistose,  hard,  and  siliceous 
and  has  an  appearance  of  greater  age  than  the  usual  types  of  green- 
stone. 


SEDIMENTARY  ROCKS. 


29 


LATOUCIIE  ISLAND. 

The  geology  and  topography  of  parts  of  Latoiiche  Island  are  sliown 
on  the  special  map  (IM.  XII)  and  in  figures  2 and  3.  The  long  axis 
of  the  island  trends  northeast  and  southwest,  and  this  is  the  general 
strike  of  the  rocks  of  the  island.  These  rocks  are  in  the  main  gray- 
Avackes  and  slates  of  the  Orca  group.  Near  the  south  end  are  some 
basic  dikes,  and  near  the  northeast  corner  of  the  island  a small 
amount  of  gabbro  has  been  intruded  into  the  sediments. 

Conglomerate  occurs  especially  on  the  point  southwest  of  the  dock 
of  the  Bonanza  mine.  The  matrix  of  the  conglomerate  is  a coarse- 


Figure  2. — Map  and  section  of  the  northwest  end  of  Latouche  Island,  showing  the  dis- 
trict just  northeast  of  that  shown  on  Plate  XII.  The  horizontal  and  vertical  scales 
of  the  section  are  the  same. 


grained  graywacke,  and  the  jiebbles  are  well  rounded  and  vary  in  size 
up  to  those  a foot  in  diameter.  Vein  quartz  and  slate,  black  and  gray 
in  color  and  in  places  flinty,  are  the  common  pebbles.  Other  pebbles 
are  fine-grained  gray  granites  of  at  least  four  types ; white  and  gray 
quartzites;  hard  silicified  quartz  porpliA^ries  and  trachytes,  and  more 
basic,  porphyritic  rocks  that  are  probably  andesites.  The  slates  of  the 
island  are  usually  black  in  color,  and  are  well  exposed  about  the 
shores  of  Wilson  Bay.  Slates  are  more  common  near  the  northwest 
shore  of  the  island,  and  grayAvackes  are  abundant  on  the  north- 


30  RECONNAISSANCE  OE  PRINCE  WILLIAM  SOUND,  ALASKA. 


/ 


western  slopes  of  the  mountains. 
At  the  Bonanza  mine  the  ore  oc- 
curs chiefly  in  fractures  in  a ha"rd, 
almost  flinty  aphanitic  rock  which 
is  gray  to  greenish  in  color.  The 
origin  of  this  rock  is  not  clear, 
but  it  is  probably  a highly  sili- 
ceous sediment.  At  the  Blackbird 
claim  are  some  intensely  sheared 
greenish  rocks  which  may  have 
originally  been  basic  igneous 
rocks. 

The  rocks  of  Latouche  Island 
have  been  subjected  to  close  fold- 
ing, the  axes  of  the  folds  trend- 
ing northeast  and  southwest.  In 
some  places,  especially  toward  the 
center  of  the  island,  the  folding 
has  been  more  intense  and  some 
of  the  folds  have  been  overturned 
slightly  to  the  southeast.  The 
axes  of  a number  of  the  folds  are 
shown  on  Plate  XII.  Superim- 
posed on  these  folds  are  other  gen- 
tle ones  whose  axes  trend  about 
at  right  angles  to  the  axes  of  the 
main  folds.  On  the  northeast 
end  of  the  island  the  main  folds 
are  more  open  and  the  cross  folds 
are  more  distinct.  (See  fig.  2.) 
The  conglomerate  exposures  de- 
scribed above  are  from  the  strati- 
graphically  lowest  rocks  on  the 
island  and  are  regarded  as  mark- 
iim  a main  anticlinal  axis.  This 
same  belt  of  conglomerate  oc- 
curs near  the  entrance  to  Wil- 
son Bay,  and  probably  also  out- 
crops about  a quarter  of  a mile 
southeast  of  Horseshoe  Bay,  where 
a number  of  loose  blocks  of  the 
conglomerate  were  found.  The 
general  structure  of  the  north- 
western part  of  Latouche  Island 
is  shown  by  the  sections  in  fig- 


SEDIMENTARY  ROCKS. 


31 


lire  3.  It  is  not  improbable  that  dip  faults  complicate  the  structure, 
but  owing  to  the  monotonous  lithology  such  faults  are  not  easy  of 
location. 

HOODOO  ISLAND, 

The  southwest  end  and  the  west  and  north  sides  of  Hoodoo  Island 
have  many  exposures  of  greenstone  with  some  interbedded  slate.  At 
the  northeast  corner  of  this  island  is  a small  elongated  island  called 
Observation  Island.  Here  and  for  half  a mile  to  the  west  are  excel- 
lent exposures  of  slate  and  graywacke  with  no  greenstone.  Just  south 
of  this  small  island  is  an  anticline,  200  feet  across,  of  conglomerate. 
The  axis  of  the  anticline  pitches  10°  N.  7°  W.  and  the  dips  on  either 
side  of  the  axis  run  up  to  45°.  The  conglomerate  is  clearly  inter- 
bedded with  the  slate  and  gra}^wacke.  The  pebbles  are  well  rounded 
and  vary  in  size  up  to  those  8 inches  in  diameter.  The  pebbles 
are  composed  of  quartz,  quartzite,  graywacke,  flint,  slate,  quartz 
porphyry,  and  trachyte.  This  conglomerate  and  its  pebbles  resemble 
closely  the  conglomerate  of  the  exposures  on  Latouche  Island,  and  it 
is  thought  to  belong  near  the  base  of  the  Orca  group.  To  the  south 
of  Observation  Island  the  conglomerate  and  interbedded  slates  and 
graywackes  continue  along  the  shore  of  Hoodoo  Island  for  about  2 
miles.  These  rocks  occur  in  a series  of  folds,  the  anticlines  of  which 
are  the  more  prominent.  The  axes  of  these  folds  average  about 
horizontal  and  strike  a little  east  of  north.  The  west  limbs  of  the 
anticlines  have  a dip  of  30°  to  50° ; the  east  limbs  are  steeper,  in  some 
places  nearly  vertical. 


ELRINGTON  ISLAND. 

Near  the  southern  part  of  Elrington  Island,  opposite  a smaller 
island  about  three-quarters  of  a mile  in  diameter  which  is  connected 
with  the  main  island  at  low  tide,  are  exposures  of  conglomerate,  gray- 
wacke, slate,  and  greenstone.  At  the  southeast  are  greenstones  and 
black  to  gray  slate,  apparently  interbedded.  The  strike  of  the  slate 
is  northeasterly  and  the  dip  35°  to  55°  NW.  The  pebbles  of  the  con- 
glomerate are  well  rounded  and  consist  of  quartz,  flint,  quartz 
porphyry,  flne-grained  granite,  quartz  schist,  and  trachyte.  No 
pebbles  exactly  like  the  greenstone  and  slate  were  noted.  The  con- 
glomerate is  interbedded  with  graywacke  and  exposures  of  these  two 
rocks  continue  for  half  a mile  to  the  northeast  of  this  locality,  the 
rocks  growing  flner  in  grain  as  the  beds  become  higher.  Whether 
the  conglomerate  here  represents  a newer  formation  resting  uncon- 
formably  on  the  slates  and  greenstones  noted  above  is  not  clear. 

58668°— Bull.  443—10 3 


32  RECONNAISSANCE  OF  PRINCE  WILLIAM  SOUND^  ALASKA. 


AGE  AND  CORRELATION. 

On  Prince  William  Sound  fossils  have  been  found  at  several 
localities.  The  first  were  reported  by  Schrader,®  as  follows : 

No.  3.  Northeast  shore  Hawkins  Island.  Two  specimens.  These  specimens 
appear  to  represent  portions  of  the  cone  of  a Glyptostrohus  or  possibly  a 
Sequoia.  The  form  of  the  cone  can  not  be  made  out,  as  the  only  portions 
remaining  are  a number  of  scales.  If  the  appearance  is  not  deceptive,  these 
fragments  are  quite  like  certain  Upper  Cretaceous  or  Lower  Tertiary  forms, 
but  are  too  indefinite  to  be  of  much  value. 

No.  20.  Gravina  Point,  east  shore  of  Prince  William  Sound.  These  are  very 
small  fragments  covered  with  remains  of  fragments  of  plants,  the  nature  of 
which  can  not  be  made  out. 

No.  24.  Johnstone  Point,  north  coast  Hinchinbrook  Island,  Prince  William 
Sound.  The  specimen  is  covered  with  a disconnected  mass  of  fragments  that 
have  very  little  character.  There  is,  however,  one  piece  that  has  somewhat  the 
appearance  of  a branch  of  a conifer.  It  has,  or  appears  to  have,  three  leaves 
attached  to  a branchlet  and  is  not  unlike  Sequoia  or  Taxodium.  It  is  too 
imperfect  to  be  of  any  value  in  determining  age. 

Schrader  and  Spencer  ^ make  the  following  statement: 

Other  plant  remains  were  seen  in  Jackson  Cove,  on  Glacier  Island,  during 
the  fall  of  1900,  but  no  recognizable  specimens  could  be  collected. 

Other  fragments  of  plants  have  been  found  on  Simpson  Bay,  but 
these  were  too  much  altered  to  allow  careful  determination  of  their 
characters. 

The  Harriman  Expedition  reported  the  finding  of  a worm  tube 
{Terehellina  palachei  Ulrich)  in  a bowlder  from  the  moraine  of  the 
Columbia  Glacier.® 

Several  similar  worm  tubes  were  found  near  the  end  of  the  -point 
just  north  of  the  entrance  to  Galena  Bay.  This  locality  is  shown 
in  Plate  VII,  B,  The  fossils  occurred  in  loose,  angular  rock  frag- 
ments on  the  beach.  These  fragments  are  similar  to  the  rock  in 
place  here,  but  none  of  the  worm  tubes  Avere  found  actually  in  rock 
in  place.  There  is,  however,  no  reasonable  doubt  as  to  their  belong- 
ing here. 

In  a coarse-grained  gray  limestone,  found  on  the  dump  of  the 
Banta  shaft  of  the  Reynolds-Alaska  Development  Company,  east 
of  Horseshoe  Bay  of  Latouche  Island,  are  a number  of  indistinct 
forms  which  may  be  the  remains  of  organisms.  The  rock  un- 
doubtedly came  from  this  shaft  and  probably  from  a depth  of  about 

® Schrader,  F.  C.,  A reconnaisance  of  part  of  Prince  William  Sound  and  the  Copper 
River  district,  Alaska,  in  1898  : Twentieth  Ann.  Kept.  U.  S.  Geol.  Survey,  pt.  7,  1900, 
p.  406.  • 

Schrader,  F.  C.,  and  Spencer,  A.  C.,  The  geology  and  mineral  resources  of  a portion 
of  the  Copper  River  district,  Alaska,  a special  pul)lication  of  the  U.  S.  Geol.  Survey, 
1901,  p.  69. 

c Harriman  Alaska  Expedition,  vol.  4,  1904,  p.  134, 


IGNEOUS  ROCKS. 


33 


100  feet  below  the  surface.  These  specimens  were  submitted  to  E.  M. 
Kindle,  who  reports  as  follows  concerning  them : 

The  rock  is  so  greatly  altered  that  it  would  be  hazardous  to  assert  positively 
that  the  supposed  fossils  iu  it  are  corals.  However,  the  numerous  cavities  in 
the  specimens  rather  strongly  suggest  that  they  represent  the  impressions  of 
partly  obliterated  corals  of  the  Favosites  type.  The  very  thin,  closely  spaced 
plates  in  the  tube-like  cavities  appear  to  represent  the  septa  in  some  species  of 
Favosites.  Corals  of  this  general  type  are  common  in  the  Devonian  and 
Silurian  and  are  not  entirely  unknown  in  the  Ordovician.  If,  therefore,  the 
supposition  that  the  impressions  are  corals  be  correct,  it  is  not  practicable  to 
draw  from  them  any  more  precise  conclusion  than  that  the  horizon  represented 
belongs  to  the  Paleozoic. 

At  Controller  Bay,  about  80  miles  southeast  of  Prince  William 
Sound,  and  also  at  Yakutat  Bay,  some  160  miles  farther  southeast,  a 
series  of  rocks  occur  which  are  similar  in  general  characters  to  the 
sediments  of  the  Orca  group  on  Prince  William  Sound.  A similar 
graywacke  and  slate  formation  extends  southwestward  from  Prince 
William  Sound  along  Kenai  Peninsula  and  occurs  again  on  Afognak 
and  Kodiak  islands.  All  these  rocks  appear  to  be  pre-Tertiary  in 
age,  and  they  have  been  grouped  together  as  the  Yakutat  “ series.”® 
This  grouping  is  based  on  the  general  character  of  these  rocks,  on 
their  relation  to  other  terranes,  on  their  approximate  continuity,  and 
especially  on  the  occurrence  in  them  at  Yakutat  Bay,  at  Prince  Wil- 
liam Sound,  and  at  Kodiak  Island  of  similar  worm  tubes  {Terehel- 
lina  palacliei  Ulrich).  Moreover,  at  Kodiak  Island  a number  of 
other  fossils  have  been  found,  and  Ulrich,  after  stud}dng  them,  con- 
cludes that  the  age  of  the  slates  there  is  most  probably  Lower  Juras- 
sic.^ Although  the  correlation  of  rocks  over  so  extensive  a district  by 
the  presence  of  one  fossil,  and  that  a worm  tube,  can  not  have  many 
of  the  elements  of  certainty,  still  in  the  present  state  of  knowledge 
concerning  the  stratigraphy  of  the  coast  of  the  Gulf  of  Alaska  it  is 
reasonable  to  regard  the  Orca  group  as  of  Mesozoic  and  in  part  proba- 
bly of  Jurassic  age.  It  should  be  borne  in  mind,  however,  that  on 
the  southeastern  ]>art  of  Kenai  Peninsula  there  are  most  probably  two 
discordant  formations  of  very  similar  lithology,  and  that  present 
information  does  not  permit  a positive  statement  as  to  which,  if 
either,  of  these  is  the  equivalent  of  the  Orca  group  or  of  the  fossili- 
ferous  slates  on  Kodiak  Island. 

IGNEOUS  ROCKS. 

GRANITES. 

The  granites  of  Prince  William  Sound  are  in  all  places  where  they 
have  been  observed  bosses  intrusive  into  much  contorted  graywackes 
and  slates.  They  were  in  but  one  locality  noted  near  any  of  the  green- 


® Harriman  Alaska  Excedition,  vol.  4,  1904,  pp.  7,  47,  55,  125. 
Ulrich,  E.  O.,  Harriman  Alaska  Expedition,  vol.  4,  1904,  p.  132, 


34  RECONNAISSANCE  OF  PRINCE  WILLIAM  SOUND,  ALASKA. 

stones  of  the  district.  Consultation  of  the  map  (PL  II)  shows  an 
irregular  line  of  these  intrusions  extending  around  the  sound,  where 
they  usually  form  bold  topographic  features. 

GRANITE  OF  EWAN  BAY.  ^ 

The  backbone  of  the  tongue  of  land  separating  Ewan  and  Paddy 
bays  is  occupied  by  a granite  mass  which  is  probably  not  connected 
areally  with  the  Eshaniy  granite,  as  there  is  a strip  of  low  country 
joining  the  heads  of  Paddy  and  Whale  bays.  The  granite  is  light 
gray  in  color  and  is  moderately  porphyritic,  with  a rather  fine- 
grained groundmass.  The  larger  crystals  are  orthoclase,  and  the 
minerals  of  the  groundmass  are  quartz,  orthoclase,  plagioclase,  bio- 
tite,  and  very  small  amounts  of  hornblende,  magnetite,  apatite,  and 
zircon.  The  plagioclase  is  normal  oligoclase  in  composition. 

The  granite  was  nowhere  seen  in  actual  contact  with  the  surround- 
ing graywacke,  but  numerous  bowlders  of  recrystallized  graywacke 
pierced  by  aplite  dikes  give  ample  evidence  of  the  intrusive  character 
of  the  granite.  The  baked  graywacke  is  of  a grayish-brown  color 
very  characteristic  of  the  baked  gray  wackes  of  the  sound.  This  color 
IS  the  modification  of  the  gray  of  the  unaltered  graywacke  which  is 
produced  by  the  dark-brown  mica,  biotite,  developed  in  the  sediment 
by  the  metamorphic  action  of  the  intrusive  granite.  Near  the  granite 
the  .'ock  is  so  changed  that  its  sedimentary  character  is  evident  only 
by  tracing  it  away  from  the  granite  till  it  grades  into  a rock  which 
is  certainly  a sediment.  Although  completely  crystallized,  its  clastic 
character  is  easily  seen  by  means  of  the  microscope.  The  brown  color 
is  caused  by  the  multitude  of  tiny  biotite  flakes  scattered  diversely 
through  the  rock.  Bands  of  quartz  grains  coarser  than  the  adjacent 
grains  indicate  the  original  bedding.  The  quartz  grains,  together 
with  the  much  scarcer  grains  of  orthoclase  and  plagioclase,  are 
closely  fitted  to  each  other  with  interlocking  margins.  The  original 
more  rounded  grains  with  very  finely  divided  interstitial  clayey 
material  have  been  worked  over  during  metamorphism  to  this  form. 
Black  grains  of  magnetite  are  sparsely  scattered  through  the  section. 

ESHAMY  GRANITE. 

The  granite  mass  practically  surrounding  Granite  Bay  and  occu- 
pying nearly  all  of  the  neck  of  land  between  Granite  and  Eshamy 
bays  has  been  termed  the  Eshamy  granite.  Its  contact  with  the  sedi- 
ments can  easily  be  traced  from  a distance  by  the  smooth  spalled 
surface  of  the  granite  and  the  darker  color  of  the  sediments.  Where 
perfectly  fresh  the  granite  is  of  a pinkish-gray  color,  but  the  outer 
foot  with  surface  exposed  to  the  weather  is  pink,  and  the  outermost  2 
or  3 inches  is  stained  brown  by  limonite.  In  places  it  is  somewhat 
giieissic,  but  the  typical  phase  of  the  main  granite  is  of  a medium- 


lONROlTS  ROCKS. 


85 


grained  granitoid  texture.  The  darker  minerals  are  roughly  grouped 
in  irregular  patches  5 to  10  millimeters  in  diameter.  These  patches 
give  the  granite  a slightly  mottled  appearance. 

The  microscope  shows  that  a few  of  the  orthoclase  crystals  are 
slightly  porphyritic.  These  larger  crystals  are  usually  made  up  of 
zones  of  slightly  different  optical  properties.  The  zones  are  pre- 
sumably due  to  slight  differences  in  the  chemical  and  physical  condi- 
tions of  the  molten  rock  while  the  orthoclase  was  crystallizing.  Some 
of  the  crystals  have  been  broken  and  the  cracks  healed  by  secondary 
quartz. 

The  quartz  is  very  irregular  and  full  of  inclusions.  In  some  places 
the  boundaries  between  adjacent  quartz  grains  are  an  intricate  fret- 
work (PI.  IX,  ^I) , showing  that  the  grains  interlock  in  an  exceedingly 
complicated  way.  This  is  probably  due  to  a partial  breaking  up  and 
partial  cementing  of  the  quartz  during  the  deformation  of  the  rock 
as  a whole.  The  undulatory  extinction  and  anomalous  biaxial  char- 
acter of  some  of  the  quartz  show  that  it  has  been  subjected  to  great 
deformative  forces. 

Plagioclase,  biotite,  and  hornblende  are  very  prominent  in  the 
thin  section  and  give  a basic  aspect  to  the  granite.  The  plagioclase 
is  andesine-oligoclase.  It  is  closely  twinned  and  in  places  is  inter- 
gix)wn  with  individuals  of  the  same  species.  The  biotite  is  consider- 
ably more  abundant  than  the  hornblende.  The  accessory  minerals 
are  magnetite,  apatite,  zircon,  and  sphene.  These  minerals  have  a 
tendency  to  cluster  about  or  to  be  included  in  the  biotite  and  horn- 
blende. 

Locally  there  are  more  basic  phases  of  the  Eshamy  granite.  At 
the  south  side  of  the  entrance  to  Granite  Bay  the  two  phases,  acidic 
and  basic,  seem  to  have  been  mixed  while  still  in  a plastic  or  semi- 
plastic condition.  The  field  relations  show  that  the  more  acidic  phase 
was  intruded  soon  after  the  more  basic  phase. 

The  contact  between  the  granite  and  the  graywackes  is  very  sharp. 
At  the  side  of  one  dike  several  feet  wide  the  granite  becomes  a little 
more  acidic  within  a few  centimeters  of  the  contact.  The  actual 
transition  takes  place  in  a few  millimeters,  but  the  microscope  shows 
the  graywacke  substance  trailing  out  into  the  granite  for  several 
millimeters.  The  biotite  of  the  recrystallized  graywacke  is  slightly 
concentrated  in  the  first  few  millimeters  of  the  graywacke,  but  in  the 
next  few  millimeters  it  is  slightly  depleted.  Numerous  aplite  dikes 
cut  the  graywacke  and  the  granite  in  all  its  phases  for  many  feet  on 
each  side  of  the  contact. 

Near  this  locality  the  granite  cuts  a greenstone.  This  greenstone 
is  a diorite,  j)robably  derived  from  a diabase,  and  it  is  the  only  basic 
igneous  rock  noted  on  the  west  shore  of  the  sound. 


PLATE  IX. 

Photomicrographs. 


A.  Partly  granulated  quartz  with  fretted  margins,  from  Eshamy  granite; 
specimen  G 269.  X 16,  crossed  nicols. 

B.  Poikilitic  quartz  with  core  free  of  xenocrysts,  from  Esther  granite;  speci- 
men G 301.  The  black  line  incloses  the  quartz  of  the  same  orientation.  X 16, 
crossed  nicols. 

C.  Reaction  rim  of  actinolite  between  olivine  and  labradorite,  from  gabbro  on 
Esther  Island ; specimen  G 293.  X 16,  crossed  nicols. 

B.  Amphibole  cross  sections  from  dike  near  Barry  Glacier ; specimen  G 430. 
These  areas  are  now  made  up  of  chlorite,  epidote,  and  calcite,  but  their  shape 
indicates  that  these  minerals  have  resulted  from  the  alteration  of  an  amphibole, 
probably  hornblende.  X 54,  ordinary  light. 

E.  Quartz  phenocryst  fractured,  with  slight  displacement,  from  quartz  ix)r- 
phyry  of  Unakwik  Bay ; specimen  G 305.  The  secondary  quartz  healing  the 
break  is  irregular  in  its  orientation,  except  between  the  parts  of  the  phenocryst, 
where  it  was  deposited  with  the  same  orientation  as  the  phenocryst.  X 16, 
crossed  nicols. 

F.  Sliced  orthoclase  crystal  from  a squeezed  aplite  dike  on  Esther  Island; 
specimen  G 300.  The  line  AA  is  the  longer  axis  of  the  crystal,  and  there  are 
four  cross  breaks  roughly  parallel  to  the  cleavage.  X 54,  crossed  nicols. 


36 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  443  PLATE  IX 


PHOTOMICROGRAPHS. 


■ - 


X,. 


■vy 


IGNEOUS  ROCKS. 


37 


NELLIE  JUAN  GRANITE. 

The  Nellie  Juan  granite  occurs  in  the  western  part  of  the  sound, 
on  the  south  shore  of  Port  Nellie  Juan.  It  extends  along  the  shore 
for  a distance  of  about  5 miles  and  inland  for  an  unknown  distance. 
It  is  surrounded  by  the  graywackes  and  slates  of  the  Valdez  group, 
but  no  examination  of  the  immediate  contact  was  made.  The  rock 
is  of  two  distinct  types  which  grade  into  one  another.  They  are  the 
main  body  of  the  granite  and  a distinctly  porphyritic  phase.  The 
main  granite  is  very  light  pink  in  color;  the  porphyritic  phase  is  of 
a light-gray  cast. 

The  rock  is  a typical  biotite  granite  with  a small  portion  of  plagio- 
clase  which  is  a little  more  acidic  than  oligoclase.  The  phenocrysts 
(orthoclase) , as  well  as  the  smaller  feldspar  crystals,  are  as  a rule 
markedly  zonal  in  structure.  The  quartz  has  a tendency  to  segregate 
into  areas  seemingly  of  one  large  grain  but  in  reality  of  several 
small  grains. 

The  ferromagnesian  minerals  are  biotite,  of  the  variety  anomite, 
and  a less  amount  of  hornblende.  The  biotite  is  altering  to  chlorite, 
becoming  greenish  as  alteration  approaches,  but  maintaining  its 
strong  birefringence.  The  hornblende  is  commonly  twinned  parallel 
to  (100),  rarely  repeated  once  or  twice. 

Magnetite,  apatite,  zircon,  and  sphene  are  present  as  accessory 
minerals.  The  magnetite  is  almost  invariably  included  as  rounded 
grains  in  the  biotite.  There  occur  in  addition  to  these  minerals  a few 
tiny  grains  of  a warm  brown  pleochroic  mineral  which  is  probably 
allanite. 

GRANITE  OF  CULROSS  ISLAND. 

A small  area  located  about  the  middle  of  the  western  part  of  Cul- 
ross  Island — that  is,  on  the  east  side  of  Culross  Passage — consists  of 
granite  associated  with  a basic  granitoid  rock  which  might  on  casual 
observation  be  mistaken  for  a phase  of  the  granite.  This  rock  is  a 
somewhat  altered  gabbro  rather  high  in  plagioclase  feldspar  (labra- 
dorite)  and  with  a partial  ophitic  texture.  It  may  be  a differentiation 
phase  of  the  granite,  which  itself  is  of  a distinctly  basic  type,  but  the 
general  relations  point  to  its  being  a separate  intrusion  not  related 
immediately,  at  least,  to  the  granite. 

The  granite  proper  has  been  intruded  into  slates  and  gra^^wackes. 
Beautiful  contact  features  with  graywackes  may  be  seen  on  the  beach 
at  the  northern  limit  of  the  granite.  The  granite  is  rather  dark  gray 
in  color,  owing  to  the  liberal  portion  of  biotite  present.  The  color 
changes  to  pink  and  light  brown  as  weathering  progresses. 

The  quartz  is  very  irregular  in  outline.  It  shows  marked  undula- 
tory  extinction  and  contains  numerous  sheets  and  lines  of  inclusions 
which  are  roughly  parallel  throughout  the  section.  The  orthoclase 


38  RECONNAISSANCE  OF  PRINCE  WILLIAM  SOUND,  ALASKA. 


and  soda-lime  feldspar  are  both  somewhat  altered  to  sericite.  The 
plagioclase  is  not  constant  in  composition,  but  there  is  a variation 
from  nearly  pure  albite  in  some  individuals  to  oligoclase-albite  in 
others.  The  average  composition  of  the  plagioclase  is  about  Abg5An^5. 

The  biotite  is  the  variety  anomite  and  is  altering  to  actinolite. 
Magnetite,  apatite,  zircon,  and  sphene  are  not  uncommon.  Eare 
small  broAvn  grains,  probably  allanite,  occur  associated  with  the 
biotite. 

Aplitic  phases  of  the  granite  are  finer  grained  and  lighter  in 
color  than  the  main  granite.  The  latter  fact  is  due  to  the  decrease 
in  the  quantity  of  the  biotite.  The  most  notable  feature  of  'this 
aplite  is  the  white  acidic  band  or  zone  at  the  immediate  contact 
with  the  graywackes.  At  a distance  of  about  1 centimeter  from  the 
contact  the  quartz  begins  to  increase  and  the  biotite  to  decrease. 
Orthoclase  also  replaces  the  plagioclase  in  part.  At  2 to  3 milli- 
meters from  the  contact  the  biotite  abruptly  disappears  except  for 
an  occasional  isolated  individual,  and  the  quartz  becomes  strongly 
predominant.  The  actual  transition  to  the  grayAvacke  takes  place 
in  0.2  to  0.3  millimeter.  For  a distance  of  15  millimeters  from  the 
contact  there  is  no  apparent  change  in  the  degree  of  anamorphism 
in  the  graywacke.  However,  the  baking  is  less  at  several  feet  from 
the  contact,  but  the  further  gradation  into  unaltered  graywacke  was 
not  observed. 

The  metamorphosed  graywacke  presents  even  to  the  unaided  eye 
decisive  evidences  of  anamorphism  in  its  Avell-marked  crystallinity 
and  in  the  presence  of  biotite,  presumably  deA^eloped  from  the  orig- 
inal clayey  constituents.  The  general  color  is  a little  lighter  gray 
than  the  ordinary  graywacke  observed  in  the  district.  Countless 
spangles  of  biotite  appear  on  the  fractured  surface. 

GRANITE  OF  PASSAGE  CANAL. 

On  the  north  side  of  Passage  Canal  is  a mass  of  gray  granite 
roughly  elliptical  in  outline  about  4 miles  long  and  2 miles  Avide. 
From  a point  4 miles  Avest  of  Point  Pigot  it  is  exposed  for  2 miles 
westward  along  the  shore.  The  northern  part  of  the  mass  is  hidden 
under  a glacier.  Near  the  contact  on  the  east  the  granite  is  much 
fractured,  as  are  also  the  adjoining  grayAvacke  and  slate,  though  to 
a less  degree  than  the  granite.  The  granite  sends  a A^ery  feAV  string- 
ers of  aplite  into  the  surrounding  rock.  The  sediments  are  schistose 
at  the  contact,  becoming  hardened  at  100  feet,  and  further  grading 
into  unaltered  graywacke  and  slate.  Numerbus  inclusions  of  mica 
schist,  probably  altered  fragments  of  the  sediments,  are  present  in 
the  shore  exjiosures.  Hence  it  is  probable  that  the  contact  is  in  the 
bay  not  far  from  the  shore. 


IGNEOUS  ROCKS. 


39 


The  granite  is  decimillimeter-grained,  though  a few  individual 
quartz  grains  attain  2 millimeters.  The  feldspar  is,  in  the  main, 
orthoclase,  altering  to  kaolin  and  muscovite,  but  a few  crystals  of 
plagioclase  varying  between  andesine  and  oligoclase  are  present. 
The  onh^  dark  mineral  in  the  granite  is  biotite,  in  part  altered  to 
chlorite.  Minor  amounts  of  apatite,  magnetite,  and  zircon  are 
present. 

To  the  east  of  this  granite,  near  Point  Pigot,  are  several  fine- 
grained, very  light-colored  dikes,  weathering  to  a deep  brown.  Under 
the  microscope  the  brown  material  is  seen  to  be  limonite  derived 
from  siderite.  The  major  portion  of  the  rock  is  oligoclase  and  sider- 
ite,  with  quartz  in  less  amount.  Little  or  no  orthoclase  is  present. 
Considerable  secondary  white  mica  occurs  in  the  rock.  The  siderite 
is  probably  secondary  also,  but  no  decisive  evidences  of  its  secondary 
origin  are  to  be  seen.  It  is  in  fairly  definite  patches  and  might 
possibly  be  original. 

ESTHER  GRANITE. 

The  Esther  granite  mass  occupies  the  greater  part  of  Esther 
Island,  at  the  south  end  of  Port  Wells.  It  is  one  of  the  two  largest 
granite  masses  about  the  sound.  It  presents  the  huge  spalled-off 
surfaces  so  characteristic  of  the  granites  in  this  district,  and  these 
distinctive  hills  may  be  easily  recognized  at  a distance  of  several 
miles.  All  the  phases  of  this  granite  are  more  or  less  gneissic.  Espe- 
cially is  this  true  of  the  granite  on  the  northern  and  eastern  parts  of 
Esther  Island,  where  the  gneissic  structure  is  very  pronounced. 

The  granite  is  in  most  places  slightly  porphyritic^  with  orthoclase 
phenocrysts.  The  quartz  is  very  undulatory  and  segmental  in  its 
extinction,  and  much  of  it  is  distinctly  biaxial.  The  quartz  of  the 
granite  on  the  east  side  of  the  island  is  partly  granulated.  The  mar- 
gins between  the  grains  are  of  the  intricate  character  shown  in  Plate 
IX,  A,  though  the  illustration  represents  another  granite.  In  one 
place  the  quartz  is  partly  poikilitic,  inclosing  small  crystals  of  ortho- 
clase. Plate  IX,  B,  shows  such  a quartz  grain  with  a solid  core.  The 
solid  central  part  probably  formed  before  the  small  crystals  of  ortho- 
clase, so  that  they  were  included  in  only  the  outer  part  of  the  quartz 
individual.  The  segregative  quality  of  both  the  quartz  and  the  fer- 
romagnesian  minerals  is  very  marked  in  this  granite.  The  quartz 
■ groups  can  be  distinguished  by  close  inspection  of  the  hand  speci- 
men, and  the  groups  of  dark  minerals  give  the  granite  a mottled 
appearance  in  some  localities. 

Potash  and  lime-soda  feldspars  are  present.  The  first  occurs  in 
crystals  of  two  orders  of  magnitude,  one  slightly  porphyritic,  the 
other  of  the  same  general  size  as  the  groundmass.  The  larger  ones 
and  many  of  the  smaller  ones  are  markedly  zonal  in  structure.  The 
lime-soda  feldspars  rarely  attain  the  size  of  the  phenocrysts  of  ortho- 


40  RECONNAISSANCE  OF  PRINCE  WILLIAM  SOUND,  ALASKA. 


clase.  Their  coni])osition  is  about  or  oligoclase-andesine. 

Many  of  the  crystals  have  more  acidic  rims  grading  to  about  albite- 
oligoclase  in  composition. 

The  dark  minerals  are  biotite  and  hornblende.  All  phases  of  the 
Esther  granite  have  a considerable  amount  of  biotite,  but  the  amount 
of  hornblende  varies  from  scarcely  any  to  as  much  as  the  biotite. 
The  platy  crystals  of  biotite  are  arranged  roughly  parallel  to  the 
planes  of  the  gneissic  structure  of  the  rock.  In  fact,  it  is  this  ar- 
rangement of  the  black  mica  plates  which  is  very  largely  the  cause 
of  the  gneissic  structure.  The  plates  are  so  bent  and  twisted  and  the 
edges  of  the  plates  are  so  ragged  that  the  mica  seems  to  have  been 
intensely  squeezed  by  the  neighboring  crystals.  In  other  places  the 
edges  of  one  biotite  flake  feather  out  against  another,  showing  that 
there  has  been  slipping  or  gliding  between  the  laminse  of  the  mica. 
The  hornblende  is  so  granulated  that  nearly  all  traces  of  its  original 
form  are  gone. 

The  accessory  minerals  are  magnetite,  apatite,  zircon,  and  a very 
small  amount  of  sphene. 

Many  aplitic  dikes  extend  from  the  granite  into  the  surrounding 
sediments.  One  dike  located  in  a little  bay  on  the  south  side  of  the 
island  contains  a feAv  small  red  garnets.  The  garnets  are  probably 
original,  though  the  dike  has  been  subjected  to  intense  shearing 
forces.  Microfaults  are  numerous  and  twinned  feldspars  with  bent 
laminae  are  common.  Here  and  there  the  feldspars  are  sliced  into 
several  fragments  by  breaks  along  the  cleavage  planes  (PL  IX,  F). 

On  the  east  side  of  Esther  Island  the  granite  cuts  a gabbro.  On 
the  northeast  side  of  Esther  Passage  there  is  a quartz  diorite  which 
may  be  related  to  the  granite. 

The  sediments  surrounding  the  Esther  granite  are  much  sheared 
and  metamorphosed.  On  the  north  shore  of  Esther  Passage  are 
metamorphic  sediments,  including  baked  graywacke,  mica  schist,  and 
knotenschiefer.  The  baked  graywacke  is  brown  in  color  and  com- 
posed of  a mixture  of  quartz  and  biotite  grains  with  a few  ortho- 
clase  and  plagioclase  grains.  The  rock  has  been  under  shearing 
stresses,  as  shown  by  the  curved  bands  of  minute  biotite  flakes.  The 
biotite  seems  to  be  in  the  process  of  formation  from  the  flne-grained 
matrix  between  the  larger  quartz  and  feldspar  grains.  A specimen 
of  schist  obtained  near  the  graywacke  gives  evidence  of  great  dynamic 
metamorphism  and  shows  intricate  but  obscure  folding.  It  is  dark 
gray  in  color,  speckled  with  tiny  black-mica  plates  Avhich  are  ar- 
ranged in  bands.  Besides  these  dark  bands  there  are  light-colored 
and  quartzite-like  bands.  Examination  Avith  the  microscope  shows  the 
mica  in  Avavy  bands  Avrapping  about  lighter-colored  and  harder  min- 
erals. There  are  lai’ge  grains  of  a colorless  mineral  in  these  biotite 
bands,  Avhicli  are  the  same  as  the  lightest-colored  material  in  the 


IGNEOUS  ROCKS. 


41 


hand  specimen.  This  mineral  is  sillimanite,  probably  produced  by 
the  dehydration  of  the  kaolin  of  the  original  sediment.  The  quartz 
bands  have  a distinctly  fragmental  aspect,  but  there  has  been  a large 
amount  of  granulation  of  the  original  particles.  A light-green, 
faintly  pleochroic  mineral  with  very  weak  double  refraction  is  pres- 
ent in  small  amount.  It  is  seemingly  an  alteration  product  of  the 
mica  and  is  probably  one  of  the  serpentines. 

The  granite  near  the  graywacke  contact  is  but  very  little  finer 
grained  than  the  usual  phase,  but  the  sediments  have  increased  very 
greatly  in  coarseness  of  grain  near  the  contact.  The  clastic  character 
of  the  sediments  is  still  made  evident,  however,  by  the  shapes  and 
arrangements  of  the  quartz  grains,  which  occupy  about  one-half  of 
the  thin  section.  Plagioclase  and  orthoclase  grains  occur  sparsely  in 
about  the  same  ratio  as  in  the  fresh  graywackes  of  the  district.  The 
increased  size  of  the  biotite  and  its  development  of  parallelism  to  the 
cleavage  direction,  the  close  interlocking  of  grains,  and  the  absence  of 
finer- grained  matrix  are  the  characteristics  of  this  rock  as  compared 
with  the  less  anamorphosed  rocks  of  approximately  the  same  original 
character. 

The  knotenschiefer  is  characterized  by  the  small  ellipsoids,  flat- 
tened in  the  plane  of  cleavage,  from  which  it  was  named.  These 
granules  are  from  1 to  3 millimeters  in  greatest  dimension.  They 
stand  out  on  the  weathered  surface.  The  rock  is  very  slaty  in  its 
general  aspect,  but  many  siliceous  bands  are  present.  Under  the 
microscope  the  rock  is  seen  to  be  composed  of  fine-grained  quartz, 
locally  in  veins,  small  black  irregular  patches  of  magnetite,  multi- 
tudes of  tiny  plates  of  biotite,  and,  smallest  of  all,  clouds  of  extremely 
minute  black  specks,  possibly  carbonaceous  matter.  There  is  one 
other  mineral  which  is  probably  sillimanite,  but  the  small  size  of  the 
individuals  precludes  accurate  determination  of  the  species.  The 
rods  of  this  mineral  lie  in  general  parallel  to  the  mica  plates — that  is, 
parallel  to  the  rock  cleavage.  In  the  knots  the  rods  and  quartz 
grains  are  more  abundant,  but  the  arrangement  of  the  rods  is  more 
diverse.  The  cause  of  the  knots  may  be  the  more  active  change  in 
these  places  from  original  kaolin  to  sillimanite  and  quartz.^ 

CEDAR  BAY  GRANITE. 

Cedar  Bay  is  the  main  eastern  arm  of  Wells  Bay,  in  the  north- 
central  part  of  the  sound.  The  Cedar  Bay  granite  surrounds  two- 
thirds  of  this  bay  and  forms  the  core  of  the  neck  of  land  between 
AUells  Bay  and  the  passage  northwest  of  Glacier  Island.  The  granite 
extends  well  up  into  the  head  of  the  northeast  arm  of  Wells  Bay. 
At  this  place  the  granite  of  the  main  mass — that  is,  several  hundred 

® Van  Hise,  C.  R.,  A treatise  on  metamorphism  : Mon.  U.  S.  Geol.  Survey,  vol.  47,  1904, 
pp.  816-317. 


42  RECONNAISSANCE  OE  PRINCE  WILLIAM  SOUND,  ALASKA. 


feet  from  the  contact  with  the  siiiTounding  graywacke — is  of  a light- 
gray  color.  The  size  of  grain  is  0.5  to  2 millimeters.  A few  of  the 
feldspars  are  about  one  order  larger  in  size  than  the  average  grain  of 
the  body  of  the  rock.  The  granite  is  of  a very  even  grain  and  the 
quartz  is  in  more  regular  shapes  than  that  of  the  other  granites  of 
the  sound.  The  stress  phenomena  in  the  rock  are  very  slight.  There 
are  no  fractures,  no  granulated  quartz,  no  bent  biotite  flakes,  and  very 
little  undulatory  extinction  of  the  quartz. 

The  orthoclase  is  very  irregular  in  outline  and  contains  many  tiny 
flakes  of  white  mica.  The  plagioclase  is  andesine-oligoclase, 
AbggAiigg  HI  coiuposition.  It  is  not  a very  prominent  constituent  of 
the  rock.  The  biotite  is  greenish  brown  in  color  and  is  very  largely 
altered  to  chlorite.  Small  amounts  of  hornblende,  magnetite,  apa- 
tite, and  zircon  occur  as  accessory  minerals.  In  some  localities  the 
granite  has  more  of  the  darker  minerals  than  in  others,  but  on  the 
whole  it  is  rather  acidic. 

At  the  head  of  the  small  bay  just  south  of  Cedar  Bay  the  granite 
occurs  in  two  phases.  Microscopic  examination,  however,  shows 
but  one  of  these  to  be  of  granitoid  texture.  This  phase  is  very  much 
like  the  granite  at  the  head  of  the  northeast  arm  of  Wells  Bay  in 
both  its  texture  and  its  mmeralogical  constitution.  The  other  rock 
is  very  white  in  color,  being  in  many  places  as  white  as  marble.  The 
microscope  reveals  it  to  be  a porphyry  with  microgranitic  ground- 
mass.  The  phenocrysts  occupy  about  as  much  of  the  rock  as  the 
groundmass.  They  are  quartz  and  orthoclase,  and  a small  number 
are  oligoclase.  The  groundmass  is  composed  of  the  same  minerals. 
The  remarkably  light  color  of  the  porphyry  is  caused  by  the  chalky 
aspect  of  the  feldspars,  due  to  rather  advanced  alteration,  and  by 
the  almost  complete  lack  of  dark-colored  minerals. 

The  granite  at  10  feet  from  the  contact  with  the  sediments  in  the 
northeast  arm  of  Wells  Bay  has  a subporphyritic  texture  with  ortho- 
clase phenocrysts.  The  average  size  of  grain  is  somewhat  less  than 
that  of  the  main  granite.  There  is  seemingly  no  difference  in  the 
basicity  of  the  granite.  At  10  inches  from  the  contact  the  granite 
is  a porphyry  with  decimillimeter-grained  groundmass  and  milli- 
meter-grained phenocrysts  of  quartz  and  orthoclase.  Numerous 
small  areas  of  the  groundmass  and  parts  of  some  of  the  orthoclase 
plieiiocrysts  are  micropegmatitic.  About  many  of  the  phenocrysts  the 
grain  of  the  groundmass  is  a little  finer  than  the  average.  Very 
little  plagioclase  is  present.  Biotite  occurs  in  subordinate  amount. 
Immediately  at  the  contact  the  grain  becomes  somewhat  coarser  and 
the  phenocrysts  more  abundant.  The  last  few  millimeters  are  com- 
posed only  of  quartz  and  orthoclase.  A white  band  marking  this 
contact  zone  may  be  seen  very  distinctly. 


IGNEOUS  ROCKS. 


43 


The  contacts  of  the  larger  dikes  with  the  sediments  are  the  same 
as  those  of  the  granite,  but  as  the  dikes  become  smaller  (several 
millimeters  wide)  they  become  finer  grained  and  contain  only  quartz 
and  orthoclase,  with  a rare  crystal  of  plagioclase.  In  a few  places 
a slight  mixing  of  the  baked  graywacke  particles  and  the  aplite* 
can  be  observed.  As  the  dikes  become  still  finer  they  become  more 
and  more  quartzose.  When  the  dikes  are  a few  tenths  of  a millimeter 
in  width,  only  an  occasional  orthoclase  crystal  is  present.  Those 
which  occur  are  in  general  larger  than  their  quartz  neighbors  and  are 
almost  invariably  in  simple  Carlsbad  twins.  The  very  finest  ends 
of  the  dikes  are  made  up  of  nothing  but  quartz. 

SHEEP  BAY  GRANITE. 

A granite  mass  occupies  the  northeast  third  of  the  point  of  land 
separating  Port  Gravina  from  Sheep  Bay.  It  is  light  gray  in  color 
and  is  the  coarsest-grained  granite  of  the  sound.  It  is  millimeter 
grained,. composed  of  about  one-half  quartz,  one-third  orthoclase,  and 
the  remainder  plagioclase,  biotite,  and  accessory  minerals.  The  gran- 
ite is  in  contact  with  fine-grained  baked  graywacke  at  the  head  of 
Port  Gravina. 

The  quartz  varies  from  a few  tenths  of  a millimeter  to  nearly  10 
millimeters  in  width,  averaging  about  2.5  millimeters.  It  has  strong 
undulatory  and  segmental  extinction.  In  many  places  the  quartz 
has  been  fractured  and  the  cracks  are  filled  with  fine-grained  sec- 
ondary quartz.  Lines  and  sheets  of  inclusions  are  extremely  abun- 
dant. They  traverse  from  grain  to  grain  of  the  quartz  without 
break.  There  seem  to  be  two  systems  of  these  inclusion  sheets,  whose 
directions  are  in  part  certainly  related  to  the  fracture  directions. 
Many  of  the  segments  of  the  segmental  extinction  are  bounded  by 
inclusion  sheets.  It  is  therefore  clear  that  these  inclusions  are  sec- 
ondary and  have  been  induced  by  deformative  forces  acting  upon  the 
quartz. 

The  orthoclase  is  very  irregular  in  shape,  and  as  a rule  simply 
twinned  according  to  the  Carlsbad  law,  though  the  twins  are  locally 
repeated  two  or  three  times.  It  is  quite  fresh,  except  near  the  iron- 
bearing minerals,  where  the  alteration  to  sericite  is  well  begun.  The 
larger  orthoclase  crystals  are  intergrown  with  thin,  nearly  flat  plates 
of  another  feldspar,  probably  albite. 

The  plagioclase  is  distinctly  zonal  in  its  usual  occurrence.  The 
bodies  of  the  crystals  are  oligoclase-andesine  and  the  rims  are  as 
acidic  as  sodic  oligoclase. 

The  biotite  occurs  very  commonly  in  hexagonal  plates,  by  means 
of  which  the  optical  orientation  is  found  to  be  that  of  the  variety 
anomite.  Alteration  to  chlorite  has  begun.  Hornblende  is  absent. 


44  RECONNAISSANCE  OF  PRINCE  WILLIAM  SOUND,  ALASKA. 

but  very  small  amounts  of  magnetite,  apatite,  and  zircon  occur. 
Sphene  is  present  in  notable  quantity  in  connection  with  altering 
biotite.  This  fact  suggests  that  the  mica  is  probably  high  in  titanium. 

At  the  head  of  Sheep  Bay  the  granite  has  a larger  proportion  of 
ferromagnesian  minerals.  The  rock  has  been  much  mashed  in  the 
zone  of  fracture.  Some  of  the  mica  plates  have  been  intensely  sheared, 
and  many  of  the  brittle  minerals  have  been  partly  granulated. 

OTHER  GRANITE  AREAS. 

In  addition  to  the  granites  described  above,  a few  small  occurrences 
are  known.  The  first  of  these  is  the  granite  on  the  west  side  of  Port 
Bainbridge,  near  the  head  (see  PI.  II),  at  a distance  of  to  2 
miles  from  the  shore.  It  forms  the  top  of  the  first  ridge  west  of  the 
port.  It  was  not  visited,  nor  were  specimens  procured  from  fhe 
glacial  streams  coming  down  from  the  glacier  which  covers  a third 
of  the  granite  area.  The  granite  is  much  lighter  in  color  than  the 
surrounding,  mountains  of  gray wackes  and  slates.  Its  smooth,  spalled- 
off  sides  and  rounded  top,  features  very  characteristic  of  the  granitic 
hills  of  the  district,  and  its  distinct  contact  with  the  darker  rocks 
serve  to  distinguish  it  with  little  doubt  as  an  intrusion  of  acidic 
igneous  rock.  The  small  granite  mass  peeping  from  under  the 
glacier  miles  northeast  of  the  granite  just  described  may  be  part  of 
the  same  body,  as  both  disappear  under  but  on  opposite  sides  of  the 
same  ice  field. 

On  the  west  side  of  Glacier  Bay  is  a small  boss  of  fine-grained 
granite  porphyry  composed  of  quartz  and  orthoclase,  with  a small 
amount  of  brown  mica  and  green  hornblende.  Plagioclase  is  very 
sparsely  scattered  through  the  rock.  A peculiar  feature  of  this  gran- 
ite is  the  presence  of  slightly  lighter  colored,  oval  areas  several  centi- 
meters wide,  in  which  occur  radial  aggregates  of  a dark-green  or 
black  mineral.  The  phenocrysts  in  these  places  are  slightly  larger 
and  more  abundant  than  in  the  body  of  the  rock.  This  dark  mineral 
is  probably  an  occurrence  of  tourmaline  somewhat  similar  to  that  in 
the  granite  of  Stone  Mountain,  De  Kalb  County,  Ga.,  described  by 
Watson.®  The  biotite  is  more  abundant  in  these  places  and  is  of  a 
distinctly  green  color. 

SUMMARY. 

The  subjoined  tables  show  the  mineralogical  and  chemical  charac- 
ters of  four  of  the  granites  as  determined  by  estimation  of  the  relative 
quantities  of  each  mineral  in  two  to  four  selected  thin  sections  by  the 
Rosiwal  method.^  The  computation  of  the  norm  and  the  quantitative 
classification  are  according  to  Cross,  Iddings,  Pirsson,  and  Washing- 

“ Watson,  T.  L.,  The  granitic  rocks  of  Georgia  and  their  relationships  : Am.  Geologist, 
VOl.  27,  1901,  pp.  206-207. 

**  Rosiwal,  Verb.  Wien.  Geol.  Reichs-Anst.,  vol.  23,  1898,  p.  143. 


IGNEOUS  EOCKS. 


45 


ton.®  Although  these  results  are  but  approximations  of  the  true 
compositions  of  the  granites,  they  give  a fairly  definite  idea  of  their 
characters.  The  composition  of  the  biotite  and  hornblende  of  the 
Esther  granite  was  assumed  to  be  the  same  as  that  of  like  minerals  in 
a similar  rock  from  Butte,  Mont.  The  composition  of  the  biotite  and 
hornblende  of  the  Nellie  Juan,  Cedar  Bay,  and  Sheep  Bay  granites 
was  assumed  to  be  the  same  as  that  of  like  minerals  from  somewhat 
similar  rocks  from  the  Yosemite  Valley,  California. 


Average  chemieal  eonipositions  of  the  NelUe  Juan,  Esther,  Cedar  Bay,  and 

Bheep  Bay  granites. 


Nellie  Juan 
granite. 

Esther 

granite. 

Cedar  Bay 
granite. 

Sheep  Bay 
granite. 

SiOz 

72.7 

66.7 

77.6 

79.4 

AI2O3 

13.8 

13.6 

11.7 

10.1 

FezOs 

.67 

1.4 

.2 

.45 

FeO 

1.43 

3.0 

.3 

1.07 

MgO 

.9 

2.9 

.3 

.8 

CaO 

1.6 

3.6 

1.5 

1.6 

NazO 

1.3 

1.6 

.8 

.7 

KzO 

7.4 

4.9 

7.3 

5.4 

HzO 

.2 

.8 

.1 

MnO 

.1 

.1 

100. 00 

98.6 

99.7 

99. 62 

Average  fnineral  compositions  {modes)  and  norms  of  the  NelUe  Juan,  Esther, 
Cedar  Bay,  and  Sheep  Bay  granites. 


Nellie  Juan 
(I,  4,  2,  2). 

Esther  (II,  4,  3,  2). 

Cedar  Bay 
(I,  3,  2,  1). 

Sheep  Bay 
(I,  3,  2,  2). 

Mode. 

Norm. 

Mode. 

Norm. 

Mode. 

Norm. 

Mode. 

Norm. 

Quartz 

Orthoclase 

33.1 
39.0 
j AbyaAiizs 
\ 18.8 
(11.3) 
(7.5) 
8.6 
.4 

29.5 

44.5 

30.7 
19.2 

AbesAnsa 

25.8 
(12.5) 
(13.3) 

17.1 

7.1 

27.6 

27.8 

42.4 

41.5 
AbeaAnsa 

13.2 

(6.5) 

(6.7) 

2.3 

.5 

40.6 

44.5 

50.4 
29.7 

AbeaAnss 

12.4 
(6.0) 
(6.4) 

4.7 

2.6 

48.6 

33.4 

Plagioclase 

Albite 

Anorthite 

Biotite 

10.5 

11.1 

10.5 

16.7 

5.2 

8.3 

5.2 

8.3 

Hornblende 

MgSiOs 

2.0 

2.0 

.9 

7.0 

6.3 

2.3 

’"'l.‘6' 

.4 

.2 

2.0 

1.5 

.7 

FeSiOs 

Magnetite 

.1 

.1 

.22 

100.0 

100. 5 100. 0 

97.2 

99.9 

100.2 

100.  02 

99.7 

According  to  the  quantitative  classitication  tlie  Nellie  Jnan  granite  belongs  to 
Class  I (persalane),  order  4 (brittanare),  rang  2 (toscanase),  siibrang  2 (del- 
lenose).  The  rock  may  then  be  spoken  of  as  a somewhat  pbyric  granodellenose. 
The  Esther  granite  belongs  to  Class  II  (dosalane),  order  4 (anstrare),  rang  3 
(tonalase),  and  snbrang  2 (dopotassic) . The  rock  may  be  called  a granodopo- 
tassic  tonalase,  or  in  other  words,  a rather  basic  biotite-hornblende  granite 
gneiss.  The  mode  is  decidedly  biotitic.  This  rock  is  a little  more  potassic 
than  the  typical  tonalite,  but  it  might  be  called  a biotite-orthoclase  tonalite. 
The  Cedar  Ray  granite  belongs  to  Class  I (persalane),  order  3 (colnmbare),  but 
very  near  to  order  4 (brittanare),  rang  2 (alsbachase),  and  subrang  1 (barely 


“ Cross,  Whitman,  Iddings,  J.  P.,  Pirsson,  L.  V.,  and  Washington,  H.  S.,  Quantitative 
classification  of  igneous  rocks,  1903, 


46  EECONNAISSANCE  OF  PRINCE  WILLIAM  SOUND,  ALASKA. 


perpotassic).  It  is  therefore  a granoperpotassic  alsbachase,  close  to  the  alaskite 
group.  The  small  amount  of  femic  minerals  gives  this  rock  a normative  mode. 
The  Sheep  Bay  granite  is  the  most  acidic  of  the  four  granites  classified.  It 
belongs  to  Class  I (very  persalane),  order  3 (columbare),  rang  2 (alsbachase), 
and  subrang  2 (mihalose),  near  subrang  1 (perpotassic).  The  rock  is  hence 
a granomihalose  and,  like  the  Cedar  Bay  granite,  is  near  the  alaskite  group. 

A study  of  the  tables  shows  that  the  four  granites  there  listed  are  of  two 
major  types.  The  first  of  these  is  the  Esther  granite.  This  granite  is  very 
much  less  acidic  than  the  others.  It  is  also  low  in  potassium  or  orthoclase,  with 
a correspondingly  greater  amount  of  biotite  and  hornblende  (hypersthene  in  the 
norm)  than  the  other  three.  It  is  nearly  a tonalite  in  composition. 

The  second  group  is  represented  by  two  divisions,  the  Nellie  Juan  granite  on 
the  one  hand  and  the  Cedar  Bay  and  Sheep  Bay  granites  on  the  other.  The 
Nellie  Juan  granite  is  chemically  very  close  to  the  dellenite  of  Brbgger  and  the 
toscanite  of  \Yashington.  The  other  two  lack  but  a small  amount  of  potassium  at 
the  expense  of  lime,  magnesia,  and  iron  to  become  typical  alaskites.  The  last 
two  rocks  are  very  closely  alike,  differing  only  in  a slight  amount  of  iron  and 
potassium.  The  Sheep  Bay  granite  is  the  more  femic. 

On  the  other  hand,  the  Esther  granite  is  so  different  magmatically  that  there 
is  little  doubt  of  its  being  different  in  genesis  from  its  neighbors  on  the  sound. 
The  greater  deformation  of  this  granite  and  the  greater  anamorphism  of  near-by 
sediments  suggest  that  this  granite  is  of  greater  age  than  the  others.  It  shows 
at  least  that  it  lies  in  a more  deformed  territory. 

The  relations  of  the  granites  to  the  sedimentary  rocks  of  Prince 
William  Sound  are  distinctly  intrusive,  as  shown  by  {a)  the  lack  of 
basal  conglomerates  about  the  granites,  (6)  the  anamorphosed  condi- 
tion of  the  sediments  near  the  granites,  and  (c)  the  presence  of  dikes 
leading  from  the  granites  into  the  sediments.  After  solidification  of 
the  granites  movements  have  taken  place  affecting  both  the  sediments 
and  the  granites.  This  is  most  notable  in  the  Esther  granite.  The 
small  size  of  the  granite  bosses  and  the  slight  degree  of  anamorphism 
of  the  sediments  suggest  that  the  granite  bosses  probably  do  not  en- 
large much  for  a considerable  depth.  The  lack  of  intense  anamorphic 
changes  and  the  occurrence  of  porphyritic  peripheral  phases  of  the 
granites,  as  well  as  the  absence  of  the  complicated  aplite  and  pegma- 
tite dike  systems  characteristic  of  deep-seated  intrusions,  indicate 
that  these  granites  solidified  considerably  nearer  the  surface  than  is 
common  with  granitic  intrusions. 

The  granites,  with  the  possible  exception  of  the  Sheep  Bay  granite, 
are  not  associated  with  the  greenstones  of  the  district.  The  Esther 
granite  is  probably  the  oldest  of  the  granites  of  the  sound.  The  Sheep 
Bay  granite  is  intrusive  into  rocks  referred  to  the  Orca  group;  the 
other  granites  cut  the  Valdez  group.  The  relation  of  these  other 
granites  to  the  Orca  is  not  known. 

ACIDIC  DIKES. 

At  several  localities  around  Prince  William  Sound  isolated  acidic 
dikes  cut  the  sediments,  especially  those  of  the  Valdez  group.  Two 


IGNEOUS  ROCKS. 


47 


dikes,  one  about  3 feet  wide,  occur  on  the  southeast  shore  of  Harri- 
man  Fiord,  about  2 miles  northeast  of  its  head,  and  another  dike  3 or 
4 feet  wide  is  three-fourths  of  a mile  southwest  of  the  Toboggan 
Glacier,  The  first  two  dikes  are  flesh  pink  in  color  and  are  composed 
essentially  of  quartz,  orthoclase,  plagioclase,  and  iron  carbonate. 
The  carbonate  composes  about  one-fourth  of  the  rock.  No  suggestion 
as  to  the  origin  of  the  carbonate,  other  than  that  it  is  probably  sec- 
ondary, can  be  made  from  the  data  at  hand.  The  other  dike  is  a 
light  grayish  green,  much  sericitized  aggregate  of  feldspar  and 
quartz,  with  a few  patches  of  quartz.  The  green  color  is  caused  by 
a small  amount  of  chlorite. 

Two  dikes  outcrop  at  the  front  of  the  Barry  Glacier  on  the  east 
side.  Both  are  light  grayish  green  in  color;  one  is  finely  crystalline 
and  compact ; the  other  is  medium  grained  and  granitoid.  The  finer- 
grained  dike  contains  a few  specks  of  pyrite  and  some  dark-green 
rodlike  forms.  These  rods  (PI.  IX,  D)  are  made  of  chlorite,  epidote, 
and  calcite,  but  show  such  distinctive  amphibole  cross  sections  that 
there  is  no  doubt  of  their  having  been  originally  an  amphibole.  Both 
dikes  are  made  up  principally  of  quartz,  orthoclase,  plagioclase,  and 
smaller  amounts  of  calcite.  The  alteration  of  the  feldspars  to  mus- 
covite is  very  marked. 

On  a little  island  near  the  center  of  the  east  shore  of  Unakwik 
Inlet,  is  a flinty  gray  quartz  porphyry,  intruded  parallel  to  the  bed- 
ding of  the  adjacent  graywacke.  The  phenocrysts  are  of  quartz  and 
orthoclase  from  1 to  2 millimeters  in  size.  The  groundmass  is  centi- 
millimeter  grained,  so  fine  that  only  quartz  is  certainly  determinable. 
Crystals  of  pyrite  are  scattered  through  the  rock.  In  some  places 
the  porphyry  has  been  fractured  and  cemented  by  quartz.  Broken 
phenocrysts  of  both  quartz  and  feldspar  are  healed  either  wholly  or 
in  part  by  material  deposited  in  the  same  orientation  as  the  broken 
crystals  (PI.  IX,  E). 

On  Unakwik  Inlet,  north  of  the  mouth  of  Miners  Biver,  a quartz 
porphyry  dike  cuts  a diorite.  The  dike  has  been  intensely  granulated. 

Almost  opposite  the  conglomerate  point,  on  the  east  side  of 
Unakwik  Inlet,  are  three  acidic  dikes  cutting  the  bluffs  of  massive 
graywacke.  The  northern  two  dikes  are  close  together  and  20  and 
35  feet  wide.  They  are  composed  of  a light-colored,  slightly  por- 
phyritic  medium-grained  granite,  finer  grained  at  the  edges  of  the 
dikes  than  at  the  center.  The  major  portion  of  the  rock  is  quartz 
and  orthoclase.  In  less  amount  are  plagioclase  and  chlorite.  One- 
fourth  mile  south  of  these  dikes  is  a 25-foot  dike  of  rhyolite,  about 
parallel  to  the  others — that  is,  about  vertical  and  striking  east  and 
west.  The  phenocrysts  of  the  porphyry  are  of  rounded  quartz  and 
feldspar  crystals,  more  rarely  biotite,  up  to  15  millimeters  in  width. 

58668°— Bull.  443—10 4 


48  RECONNAISSANCE  OF  PRINCE  WILLIAM  SOUND,  ALASKA. 

The  groundmass  is  light  greenish  gray  or  brown  in  color  and  fel- 
sitic  in  appearance.  Under  the  microscope  portions  of  the  ground- 
mass  surrounding  certain  of  the  quartz  phenocrysts  have  extinction 
parallel  with  the  quartz.  The  extinction  of  the  groundmass  as  a 
whole  is  patchy.  Certain  radial  aggregates  of  spherulitic  aspect  are 
present.  These  facts  point  to  an  original  glassy  groundmass  of  the 
rock.  Hence  it  might  be  termed  an  aphorhyolite.®  Zones  of  chal- 
cedonic  quartz  partly  surround  some  of  the  quartz  phenocrysts.  The 
rock  contains  brownish  inclusions  of  fine-grained  diabase,  which 
appear  to  be  fragments  of  wall  rock.  The  inclusions  examined  were 
either  brought  up  from  some  diabase  below  or  are  very  thoroughly 
crystallized  fragments  of  graywacke. 

A dike  of  porphyritic  rhyolite  with  spherulitic  groundmass  was 
noted  by  Emerson  ^ on  the  nunatak  in  the  Columbia  Glacier. 

In  1898  Schrader®  mentioned  certain  gray  granitic  dikes  on  the 
Giant  Rocks,  Port  Valdez,  and  near  the  Valdez  Glacier.  The  latter 
were  not  visited  by  this  party.  The  dikes  on  the  Giant  Rocks  are 
in  a sheared,  somewhat  schistose  graywacke.  The  specimen  from 
this  locality  is  an  orthoclase  porphyry  in  Avhich  most  of  the  rock  is 
made  up  of  small  orthoclase  phenocrysts.  Quartz  occupies  nearly 
all  of  the  space  between  the  phenocrysts.  The  peculiar  texture  of  this 
rock  gives  the  fractured  surface  a roughness  seemingly  due  to  the 
breaking  of  the  rock  between  the  phenocrysts  rather  than  across  them. 
The  weakened,  partly  granulated  quartz  is  probably  the  cause  of  this 
peculiar  fracture. 

A dike  about  125  feet  wide  occurs  on  the  east  side  of  the  entrance 
to  Valdez  Narrows.  It  is  composed  mostl}^  of  quartz  and  orthoclase 
with  a little  plagioclase.  A sulphide,  probabU  pyrite,  is  distributed 
rather  uniformly  through  the  rock.  The  sulphide  is  usually  accom- 
panied by  a few  chlorite  flakes. 

BASIC  INTRUSIVE  ROCKS. 

Several  occurrences  of  diorite,  diabase,  and  gabbro  in  the  form  of 
dikes  and  sills,  cutting  the  graywackes  and  slates  of  both  the  Valdez 
and  the  Orca  groups,  were  observed  on  Prince  William  Sound.  It 
is  probable  that  these  dikes  and  sills  were  in  part,  at  least,  the  feeders 
of  the  extensive  surface  flows  of  basic  lavas  during  earlier  Orca  time. 
A few  of  the  more  important  occurrences  Avill  be  described. 

® Bascom,  Florence,  The  ancient  volcanic  rocks  of  South  Mountain,  Pennsylvania : Bull. 
U.  S.  Geol.  Survey  No.  136,  1896,  p.  42. 

^ Emerson,  B.  K.,  Harriman  Alaska  Expedition,  vol.  4,  1904,  p.  25. 

^ Schrader,  F.  C.,  A reconnaissance  of  a part  of  I*rince  Wiliiam  Sound  and  the  Copper 
River  district,  Alaska,  in  1898  : Twentieth  Ann.  Rept.  U.  S.  Geol.  Survey,  pt.  7,  1900, 
p.  409. 


IGNEOUS  KOCKS. 


49 


GABBROS. 

GABBRO  ON  ESTHER  ISLAND. 

On  the  east  side  of  Esther  Island  there  occurs  a gabbro  older  than 
the  Esther  granite.  Here  there  are  the  following  rocks  in  the  order 
named,  the  oldest  first:  (a)  Mica  schist,  (h)  gabbro,  (c)  granite,  (d) 
aplite  and  pegmatite.  The  order  of  the  last  two  was  not  determined. 

This  gabbro  exists  in  several  phases.  One  phase  is  made  up 
largely  of  poikilitic  crystals  of  augite  inclosing  prismoid  crystals 
of  labradorite.  This  feldspar  is  about  the  same  in  all  the  phases  of 
the  gabbro.  It  is  beautifully  twinned,  according  to  both  the  albite 
and  pericline  laws.  Another  phase  has  in  addition  to  the  augite  and 
labradorite  a considerable  quantity  of  olivine  which  is  very  fresh. 
About  each  grain  of  olivine  (PI.  IX,  6^)  is  a zone  made  up  of  thou- 
sands of  acicular  colorless  crystals  of  actinolite.  Macroscopic  ex- 
amination of  the  rock  reveals  the  fact  that  these  nodular  portions  of 
the  rock  are  more  easily  weathered  parts  which  cause  a pitted 
weathered  surface  in  this  variety  of  the  gabbro. 

Van  Hise®  gives  the  volume  change  of  this  alteration  of  labra- 
dorite to  actinolite  as  minus  7.18  per  cent.  This,  then,  was  a change 
under  anamorphic  conditions.  Kemembering  that  the  gabbro  is 
older  than  the  granite,  and  that  the  granite  shows  marks  of  intense 
deformation,  we  may  conclude  that  this  alteration  belongs  either  to 
the  same  period  as  that  in  which  the  granite  was  deformed  or  to  the 
period  when  the  granite  was  intruded.  However,  no  mechanical 
effects  of  deformation,  such  as  granulation  or  slicing,  are  present  in 
the  gabbro. 

GABBRO  ON  LATOUCHE  ISLAND. 

On  the  east  side  of  the  point  at  the  northeast  corner  of  Latouche 
Island  is  a gabbro  dike  at  least  100  feet  wide.  The  rock  is  intruded 
into  graywackes  and  slates.  It  is  a little  finer  grained  at  the  edges 
than  in  the  middle.  It  is  composed  essentially  of  about  equal  parts 
of  diallage  and  andesine-labradorite.  Macroscopically  the  diallage 
resembles  scales  of  light-green  mica  scattered  through  the  rock.  The 
microscope  shows  that  the  rock  has  been  intensely  deformed  in  the 
zone  of  fracture.  The  feldspars  are  faulted  and  broken  in  a most 
intricate  way.  The  faults  vary  from  submicroscopic  to  those  of  sev- 
eral millimeters  displacement.  The  diallage  is  in  many  places  twisted, 
bent,  and  broken.  Both  minerals  show  marked  undulatory  extinction. 

Several  small  gabbro-pegmatite  dikes  cut  the  main  dike.  The 
grain  of  the  pegmatite  is  in  places  as  coarse  as  5 centimeters.  It  is 
composed  of  plagioclase,  augite  in  process  of  uralitization,  and  smaller 
amounts  of  ilmenite. 

“ Van  Hise,  C.  R.,  A treatise  on  metamorphism  ; Mon.  U.  S.  Geol.  Survey,  vol.  47,  1904, 
np.  310-311.  * 


50  KECONNAISSANCE  OF  PRINCE  WILLIAM  SOUND,  ALASKA. 

The  contact  of  the  gabbro  with  the  sediments  is  nearly  vertical. 
Graywacke  at  2 feet  from  the  contact  shows  but  very  little  recrystal- 
lization, though  it  is  somewhat  sheared  and  fractured. 

DIABASES. 

DIABASE  DIKES  AT  VALDEZ  NARROWS. 

About  miles  southwest  of  Entrance  Island,  on  the  east  side  of 
Valdez  Narrows,  a 2-foot  dike  of  porphyritic  diabase  is  exposed  in 
the  cliff.  The  strike  of  the  dike  is  about  east  and  west  and  it  dips 
55°  S.  The  dike  is  inclosed  in  graywacke  and  slate.  The  porphyritic 
crystals  are  probably  labradorite.  A few  small  grains  of  iron  sul- 
phide are  present.  Halfway  up  the  cliff  the  dike  is  displaced  about  its 
own  width  by  a fault  plane. 

Just  south  of  the  western  point  on  the  east  side  of  Valdez  Narrows 
is  a basic  porphyritic  dike,  10  feet  wide,  cutting  hard  graywacke 
and  graywacke  slate.  The  dike  is  a diabase  Avith  phenocrysts  of 
plagioclase  up  to  three-fourths  of  an  inch  in  diameter  in  the  center. 
The  phenocrysts  gradually  decrease  in  size  toward  the  edges  of  the 
dike  and  abruptly  disappear  at  about  18  inches  from  the  edge.  The 
outer  18  inches  of  the  dike  is  very  fine  grained  and  compact. 

DIABASE  IN  TATITLEK  NARROWS. 

Tatitlek  NarroAvs  are  in  a soft  slaty  band  of  the  Orca  group.  The 
slate  outcrops  on  each  side  of  the  narrows,  but  the  long  slender  island 
in  the  southern  part  of  the  narrows  is  made  up  of  intrusive  diabase. 
This  dike  is  harder  than  the  surrounding  slate  and  so  was  left  as  an 
elevation  in  the  narrows  when  the  slate  Avas  eroded  away.  The  orig- 
inal minerals  of  the  diabase  are  augite,  plagioclase,  at  least  as  basic  as 
andesine,  ilmenite,  and  possibly  a little  quartz.  The  rock  has  been 
somewhat  granulated  and  the  minerals  are  strongly  katamorphosed. 
The  augite  is  altering  to  hornblende  about  its  margins.  The  augite 
and  plagioclase  are  altering  to  epidote,  chlorite,  and  quartz.  Though 
an  appreciable  amount  of  quartz  is  present,  it  is  probably  derived 
altogether  from  the  alteration  of  the  original  minerals.  The  ilmenite 
is  very  largely  altered  to  leucoxene.  A feAv  small  yelloAv  grains  of 
Avhat  is  probably  a metallic  sulphide  are  scattered  very  sparsely 
through  the  rock. 

DIABASE  ON  UNAKWIK  INLET. 

At  a nickel  prospect  just  north  of  the  mouth  of  Miners  River,  on  j 
the  east  side  of  Unakwik  Inlet,  is  a mass  of  diabase  cutting  gray-  ! 
Avackes  and  slates.  The  rock  is  in  several  facies,  from  a medium-  I 
grained  diabase  to  a gabbro-pegmatite.  It  is  composed  essentially  of 
augite  and  labradorite,  Avith  considerable  amounts  of  secondary  pyr-  j 


I 


IGNEOUS  ROCKS.  51 

rhotite.  The  aiigite  is  partly  uralitized  and  the  labradorite  is  more  or 
less  clouded  with  tiny  particles  of  alteration  products. 

GREENSTONES. 

In  the  lower  part  of  the  Orca  group  basic  igneous  rocks  are  abun- 
dant. (See  PI.  II.)  They  have  been  altered  more  or  less  completely 
so  that  they  now  have  a greenish  color  and  are  grouped  for  con- 
venience under  the  term  greenstones.  These  rocks  were  originally 
basic  lava  flows,  basic  fragmental  volcanic  rocks,  and  basic  intrusive 
bodies.  In  places  shearing  has  been  prominent  in  these  rocks  and 
they  are  then  classified  as  greenstone  schists. 

The  coarser  grained  and  less  altered  of  these  rocks  still  show  plagio- 
clase  feldspars  and  traces  of  augite.  The  texture  is  commonly  ophitic 
and  the  original  rock  was  thus  a diabase.  In  some  places  the  grain 
is  coarser,  the  texture  approaches  the  granitoid,  and  the  rock  may  be 
termed  a gabbro.  Commonly,  however,  the  rocks  are  highly  altered 
and  the  augite  is  changed  to  hornblende.  Where  shearing  stresses 
have  been  prominent,  chlorite  as  well  as  hornblende  is  developed.  In 
many  localities  alteration  has  gone  so  far  that  the  original  texture 
and  minerals  are  not  recognizable. 

A very  large  part  of  the  greenstones  of  the  Orca  group  are  surface 
flows.  Their  mode  of  occurrence  has  been  described  under  the  head- 
ing “ Galena  Bay  ” in  the  special  descriptions  of  the  Orca  group. 
Many  of  these  surface  flows  are  ellipsoidal  in  character — that  is,  the 
flows  contain  many  more  or  less  ellipsoidal  masses  which  vary  from  a 
few  inches  to  10  feet  in  diameter.  These  ellipsoids  in  many  places 
make  up  almost  the  entire  flow.  Between  the  individual  ellipsoids  is 
a softer,  greenish,  locally  schistose  material  whose  original  character 
is  not  clear.  In  shape  some  of  the  ellipsoids  are  almost  spherical, 
but  they  are  more  commonly  more  or  less  flattened  in  a plane  parallel 
to  the  dip  of  the  flows.  In  some  ellipsoids  this  flattening  is  probably 
due  to  pressure  after  the  rock  was  covered  with  other  flows  or  with 
sediments;  in  others  the  flattening  appears  to  be  due  to  the  pressure 
of  one  ellipsoid  on  another  before  they  had  completely  solidified. 
Still  other  ellipsoids  are  rather  irregular  in  shape,  but  are  bounded  b}^ 
curving  planes.  Some  ellipsoids  show  a radial  structure  ( PI.  VIII,  B ) . 

The  ellipsoidal  greenstones  are  common  throughout  the  lower  part 
of  the  Orca  group.  Some  of  the  most  characteristic  exposures  occur 
both  north  and  south  of  the  entrance  to  Galena  Bay  and  are  shown 
on  Plate  VIII.  In  the  more  mountainous  parts  of  the  greenstone 
areas,  as  about  Copper  Mountain  and  on  Knight  Island,  the  ellipsoi- 
dal greenstones  are  not  so  common,  but  even  in  these  places  traces  of 
this  structure  are  recognizable  here  and  there. 

The  ellipsoidal  structure  in  basic  lava  flows  is  a not  uncommon 
feature  and  has  been  described  from  several  places.  It  is  generally 


52  RECONNAISSANCE  OF  PRINCE  WILLIAM  SOUND,  ALASKA. 

thought  that  this  structure  occurs  in  submarine  flows,  or  at  least  in 
flows  which  have  entered  water.  -The  Prince  William  Sound  ellip- 
soidal greenstones  are  very  similar  to  the  Archean  Ely  greenstone  of 
the  Vermilion  iron  range  in  Minnesota,  descriptions  of  which  have 
been  written  by  Winchell  ® and  by  Clements.^ 

ECONOMIC  GEOLOGY. 

COPPER. 

HISTORICAL  STATEMENT. 

Copper  is  the  principal  metallic  substance  found  on  Prince  Wil- 
liam Sound,  and,  in  fact,  the  only  one  of  which  shipments  of  eco- 
nomic importance  have  been  made. 

There  are  reports  that  copper  prospecting  was  undertaken  during 
the  Russian  occupation  of  Alaska,  one  specific  place  being  in  the 
mountains  of  the  western  part  of  Hinchinbrook  Island,  both  north 
and  south  of  Nuchek.  Sporadic  prospecting  is  said  to  have  been  car- 
ried on  in  the  years  between  the  end  of  the  Russian  occupation  and 
1897.  Definite  information  concerning  this  early  prospecting  is, 
however,  not  at  hand. 

The  recent  period  of  the  search  for  copper  on  the  shores  of  the 
sound  dates  from  the  staking  of  the  Gladhaugh  claim  on  the  east 
side  of  Virgin  Bay  in  1897.  This  claim  developed  into  the  Ellamar 
mine.  The  Bonanza  mine  on  Latouche  Island  was  staked  later  in  the 
same  year.  From  that  time  to  the  present  prospecting  for  copper 
has  been  active,  especially  from  1903  to  1907. 

There  are  two  mines  which  have  made  regular  shipments  for  sev- 
eral years.  These  are  the  Ellamar  mine,  at  Ellamar,  and  the  Bo- 
nanza mine,  on  Latouche  Island.  Shipments  of  several  hundred  tons 
of  ore  have  been  made  from  certain  other  properties,  as  the  Knights 
Island  Consolidated  Copper  Company,  locally  known  as  the  Hub- 
bard & Elliott  Company,  on  Knight  Island;  the  Latouche  Copper 
Mining  Company,  on  Latouche  Island;  the  Reynolds-Alaska  De- 
velopment Company,  on  Boulder  Bay  and  on  Latouche  Island;  the 
Standard  Copper  Mines  Company,  on  Landlocked  Bay;  and  the 
Three  Man  Mining  Company,  on  Landlocked  Bay.  Small  trial  ship- 
ments have  been  made  from  other  properties. 

The  mineral  production  of  the  district  for  1900  to  1908  is  shown  in 
the  following  table.  The  production  before  1900  was  small.  Un- 
fortunately, the  figures  for  the  years  previous  to  1905  are  not  very 
reliable,  for  it  was  not  until  that  year  that  the  Survey  began  the 
collection  of  statistics  for  Alaska  directly  from  the  producers. 

" Winchell,  N.  II.,  The  Kawishiwin  agglomerate  at  Ely,  Minn.  : Am.  Geologist,  vol.  9, 
1892,  pp.  359-3G8. 

**  Clements,  J.  Morgan,  The  Vermilion  iron-hearing  district  of  Minnesota  : Mon.  U.  S. 
Geol.  Survey,  vol.  45,  1903,  pp.  144-150. 


COPPER. 


53 


Mineral  pf'oduction  of  Prince  William  (^ound,  1900-U)0H. 


Year 

Silver,  n 

Gold,  a 

Copper. 

Percent- 
age of 
copper 
per  ton. 

Ounces. 

Value. 

Ounces. 

Value. 

Pounds. 

Value. 

1900  

1 

250, 000 

360,  000 
1,200, 000 
2, 043, 586 
1,580,379 
2, 109, 232 
1,549,972 
1,324,963 

$40,  000 

41,000 
156,000 
275, 676 
246, 539 
407,082 
309, 994 
174, 895 

1901  

1902  

1903 

1904 

1905 

1900 

5,307 
7,  900 
8, 954 

$3, 555 
5,214 
4,745 

870. 75 
1, 156. 09 
56.74 

$18, 000 
23,  899 
1,173 

4.1 

4.4 

4.9 

1907 

1908 

10, 418, 132 

1,651,186 

4.4 

" Statistics  for  gold  and  silver  output  are  available  only  since  1905. 


ORE  INIINERALS. 

Chalcopyrite  is  by  all  means  the  most  important  copper-bearing 
mineral  on  the  sound.  It  is  present  in  practically  all  the  mines  and 
prospects  and  is  the  mineral  which  forms  the  ore  of  all  the  large 
shipments.  It  occurs  in  rather  finely  granular  form  and  its  bright- 
yellow  color  makes  it  easy  of  recognition.  In  some  of  it  the  grain  is 
very  fine  indeed. 

The  chalcopyrite  is  in  general  intimately  mixed  with  pyrrhotite, 
which  in  itself  probably  bears  a little  copper  sulphide  as  an  impurity. 
These  two  minerals,  chalcopyrite  and  pyrrhotite,  are  practically 
everywhere  present,  and  the  relative  proportions  of  the  two  vary 
greatly,  not  only  in  adjoining  deposits  but  in  the  same  deposit.  It 
is  a common  feature  in  any  one  vein  to  find  abrupt  variations  from 
point  to  point  in  the  abundance  of  these  two  minerals,  at  one  place 
the  vein  being  almost  entirely  pyrrhotite  and  close  by  almost  entirely 
chalcopyrite. 

With  the  two  minerals  just  mentioned,  but  occurring  in  much  less 
abundance,  is  pyrite,  which  also  probably  carries  a little  copper.  The 
pyrite  is  usually  granular  in  form,  and  locally  the  grain  is  very  fine, 
as  at  the  Duchess  tunnel,  near  Horseshoe  Bay,  on  Latouche  Island. 
In  places  pyrite  occurs  in  crystals  from  a quarter  of  an  inch  to  nearly 
an  inch  in  diameter;  such  crystals  are  especially  noticeable  at  the 
Bonanza  mine,  where  they  exist  in  the  form  of  pentagonal  dodecahe- 
drons which  have  their  crystal  l)oundaries  sharply  marked  and  are 
included  in  almost  solid  chalcopyrite.  Some  of  the  crystals  of  pyrite 
at  the  Bonanza  mine  are  surrounded  by  a thin  film  of  quartz,  or  of 
quartz  mixed  with  a small  amount  of  chalcopyrite.  These  crystals 
of  pyrite  also  occur  rarely  at  the  Ellamar  mine. 

Secondary  (surface)  copper  minerals  are  not  of  great  importance, 
as  weathering  has  extended  only  a small  distance  from  the  surface. 
Such  minerals  are  malachite,  which  occurs  as  green  stains  in  very 


54  RECONNAISSANCE  OF  PRINCE  WILLIAM  SOUND^  ALASKA. 

many  localities;  azurite,  which  is  rare;  covellite,  which  has  been 
found  at  the  Bonanza  mine;  and  native  copper,  which  has  been 
found  at  the  prospects  of  the  Three  Man  Mining  Company  on  Land- 
locked Bay,  and  also  at  the  Bonanza  mine,  where  it  is  now  being  de- 
posited as  a cement  to  gravels  in  a stream  bed  close  to  the  mine.  An 
indistinct,  powdery,  black  copper  mineral,  probably  melaconite, 
occurs  in  small  quantity  also  at  the  Bonanza  mine. 

At  the  prospects  of  the  Cordova  Copper  Company,  near  Orca, 
occur  copper  minerals  partly  different  from  those  noted  above.  Here 
are  found  not  only  chalcopyrite,  but  also  bornite,  chalcocite,  native 
copper,  cuprite,  and  malachite.  The  last  two  are  clearly  formed  by 
surface  alteration. 

Other  metallic  minerals  associated  with  the  ores  are  galena,  sphal- 
erite, and  magnetite.  Galena  occurs  in  small  amounts  at  some  of  the 
prospects  about  Landlocked  Bay,  at  the  Bonanza  mine,  and  in  a few 
other  places.  Sphalerite  also  occurs  at  Landlocked  Bay  and  at  the 
Bonanza  mine,  but  is  more  abundant  in  certain  prospects  on  Louis 
Bay  and  on  Herring  Bay  in  the  northern  part  of  Knight  Island.  It 
also  occurs  at  the  Ellamar  mine. 

The  nonmetallic  minerals  associated  with  the  ores  are  quartz,  cal- 
cite,  epidote,  chlorite,  and  other  alteration  minerals.  Quartz  is  by 
far  the  most  common. 

As  these  minerals  have  not  usually  been  deposited  in  open  cavities, 
but  occur  as  impregnations  and  as  replacements  of  the  country  rock, 
there  is  in  many  places  little  to  show  what  their  order  of  deposition 
has  been.  The  three  common  metallic  sulphides,  chalcopyrite,  pyr- 
rhotite,  and  pyrite,  usuall}^  appear  to  be  simultaneous  in  origin. 
Galena  and  sphalerite  also  occur  with  these  three,  but  are  in  places 
apparently  earlier  in  date.  Much  of  the  quartz  is  intimately  asso- 
ciated with  the  minerals  just  mentioned,  and  much  of  it  is  distinctly 
later  than  those  minerals.  Calcite  is  usually  later  than  the  others. 
Here  and  there  a few  small  veins  of  chalcopyrite  and  of  pyrrhotite  are 
seen  to  be  later  than  the  main  deposits,  but  these  are  exceptional.  In 
one  place  a small  quartz  vein  had  its  center  filled  with  pyrrhotite, 
the  quartz  projecting  into  this  mineral  in  crystal  form,  and  one  small 
vein  of  calcite  was  noted  where  pyrrhotite  formed  the  center. 

ORE  BODIES. 

GENERAL  DESCRIPTION. 

The  usual  occurrence  of  the  copper  deposits  is  in  zones  along  Avhich 
there  has  been  fracturing  of  the  country  rock.  Most  generally  this 
fracturing  has  gone  so  far  that  shearing  has  taken  place,  and  the  ore 
deposits  thus  commonly  occur  in  shear  zones.  In  these  zones  the  coun- 
try rock  is  usually  schistose.  Deposits  of  this  character  are  common 
in  the  vicinity  of  Copper  Mountain,  where  the  shear  zones  are  well 


COPPER. 


55 


developed.  They  have  been  well  exposed  at  several  points  east  of  this 
mountain,  especially  at  the  claims  of  the  Three  Man  Mining  Com- 
pany on  Landlocked  Bay.  Along  these  zones  there  has  been  min- 
eralization of  the  rock,  chalcopyrite,  and  the  associated  sulphides, 
pyrrhotite,  and  pyrite,  having  been  deposited  as  impregnations  and 
as  replacements  of  the  country  rock. 

Within  a single  shear  zone  it  is  frequently  possible  to  distinguish 
two  parts — first,  a more  or  less  solid  layer  of  metallic  sulphides,  and 
second,  the  rest  of  the  zone,  which  has  been  only  partly  impregnated 
with  these  sulphides.  The  solid  layer  is  the  most  conspicuous  and 
important  part  of  these  zones.  In  some  places  this  layer  occupies  the 
whole  of  a shear  zone,  but  very  commonly  the  other  part  of  the  zone 
is  present.  This  layer  of  nearly  solid  sulphides  is  as  a rule  sharply 
marked  off  from  the  rest  of  the  zone,  which  holds  a more  constant 
width,  while  the  sulphide  layer  has  a tendency  to  swell  and  pinch, 
in  places  disappearing  entirely.  The  thickness  of  the  sulphide 
layer  varies  from  a film  up  to  several  feet,  but  at  most  of  the  pros- 
pects thicknesses  of  over  5 feet  are  uncommon,  and  such  thicknesses 
are  as  a rule  not  of  great  extent.  The  ore  in  such  layers  ranges  from 
almost  pure  pyrrhotite  to  nearly  pure  chalcopyrite.  Pyrite  occurs, 
but  not  as  commonly  as  pyrrhotite.  Assays  of  these  layers  show 
percentages  of  copper  running  up  to  25  or  28,  but  the  average  is 
considerably  lower  than  this. 

The  sheared  rock  outside  of  the  sulphide  layer  varies  decidedly  in 
width  and  in  its  copper  content.  In  some  places  there  are  several 
feet  of  this  rock,  in  others  the  thickness  is  40  feet  or  more,  and  in  a 
few  such  places  there  is  no  sharp  boundary  between  the  sheared  rock 
and  the  unsheared  country  rock,  or  the  sheared  zone  contains  horses 
of  solid  rock.  The  copper  content  of  this  sheared  rock  is  in  some 
places  practically  nothing  and  in  others  runs  up  to  a few  per  cent. 
So  far  as  developed  there  are  no  considerable  thicknesses  of  this  rock 
which  run  over  4 per  cent  of  copper. 

The  country  rock  of  these  zones  is  mainly  greenstone,  although 
some  slate  and  graywacke  are  present,  and  in  some  places  the  shear 
zones  folloAv  closely  the  contact  of  these  sediments  with  the  green- 
stone. An  exception  to  this  statement  should  be  made  for  the 
deposits  on  Latouche  Island  and  on  the  south  side  of  Fidalgo  Bay, 
where  the  country  rock  is  slate  and  graywacke. 

In  a few  localities  there  are  rather  sharply  defined  veins  filled 
with  quartz,  pyrrhotite,  pyrite,  and  chalcopyrite.  One  of  these  Avas 
seen  on  Glacier  Island  and  one  on  the  northAvest  flank  of  Copper 
Mountain.  In  such  localities  there  Avas  apparently  an  open  cavity, 
which  was  later  filled  Avith  the  minerals  last  named,  but  eA^en  here 
there  is  no  distinct  banding  to  the  veins  and  the  minerals  are  of  one 
general  date.  It  is  improbable  that  there  Avere  eA^er  any  large  cavi- 


56  RECONNAISSANCE  OF  PRINCE  WILLIAM  SOUND,  ALASKA. 

ties  in  the  shear  zones.  The  ore  minerals  were  deposited  in  part 
along  the  shearing  planes,  but  especially  in  the  sheared  rock,  both 
by  impregnation  and  by  replacement. 

The  two  largest  ore  deposits,  those  of  the  Ellamar  and  Bonanza 
mines,  differ  from  the  shear  zones  above  described  in  some  respects. 
The  Ellamar  ore  body  is  a lens-shaped  mass,  whose  maximum  hori- 
zontal axis  is  190  feet  and  minimum  axis  80  feet.  Careful  studies  of 
this  ore  body  have  not  been  made,  but  it  seems  probable  that  it  is  of 
the  same  general  nature  as  the  solid  sulphide  layers  so  common  in 
the  usual  shear  zones.  Another  lens-shaped  body  of  this  character 
occurs  at  the  Duchess  tunnel  on  Latouche  Island.  The  Bonanza 
mine  is  apparently  along  one  of  these  same  shear  zones,  but  the  move- 
ment here  has  resulted  in  fracturing  rather  than  shearing,  and  the 
country  rock  is  in  large  amount  a very  fine  grained,  hard,  flinty  rock. 

On  Knight  Island  there  are  at  two  places  deposits  of  different 
character  from  those  described  above.  One  of  these  is  at  the  Harvey 
prospect,  north  of  the  west  arm  of  Mummy  Bay,  and  the  other  is  at 
the  prospect  of  the  Knight  Island  Copper  Company,  east  of  Barnes 
Cove  of  Drier  Bay.  This  has  been  described  by  Sidney  Paige.®  At 
these  places  the  country  rock  is  a fairly  coarse  grained  diabase  which 
has  been  impregnated  by  pyrrhotite  and  chalcopyrite. 

In  the  vicinity  of  Orca  are  some  prospects  that  are  of  still  a 
different  type  from  those  described  above.  The  country  rock  is  a 
much  crushed  reddish  amygdaloidal  basalt,  Avith  irregular  stringers 
of  epidotized  rock.  These  stringers  are  of  all  widths  up  to  2 feet, 
and  though  some  of  them  have  a veinlike  form,  striking  in  an  east- 
northeast  direction  and  standing  vertically,  most  of  them  show  no 
common  direction  of  elongation  and  pinch  out  within  short  distances. 
With  the  epidote  is  quartz.  The  ore,  which  is  native  copper,  chal- 
copyrite, bornite,  and  chalcocite,  occurs  associated  Avith  and  in  the 
epidote-quartz  stringers,  although  in  places  it  is  associated  with  the 
nonepidotized  country  rock.  The  country  rock,  its  alteration  to 
epidote-quartz  masses,  and  the  occurrence  of  copper  ore  within  these 
masses  all  resemble  conditions  in  parts  of  the  Lake  Superior  copper 
district. 

Weathering  has  extended  to  only. a short  distance,  commonly  only 
a fcAv  feet  or  even  a feAV  inches,  beloAV  the  surface  in  the  glaciated 
parts  of  the  sound,  and  all  the  copper  prospects  examined  are  in 
glaciated  territory.  There  has  thus  been  A^ery  little  surface  alteration 
of  the  ore  deposits  and  consequently  little  recent  secondary  enrichment. 

iVs  is  customary  in  many  mining  districts,  long  tunnels  haA^e  been 
driA^en  into  the  mountains  Avith  the  hope  of  cutting  at  some  depth 
ore  bodies  Avhich  outcrop  at  the  surface.  In  seA^eral  such  tunnels. 


“Bull.  II.  S.  Geol.  Survey  No.  284,  1906,  p.  85. 


COPPER. 


57 


especially  where  they  cross  the  ore  zones  at  100  feet  or  more  below 
the  surface  outcrops,  the  zones  are  found  to  be  thinner  and  much 
lower  in  copper  content.  In  fact,  in  some  places  it  is  almost  impos- 
sible to  recognize  in  the  tunnels  shear  zones  which  are  prominent 
and  carry  a considerable  copper  content  at  the  surface.  Of  course 
there  are  many  prospects  where  no  information  is  available  concern- 
ing the  character  of  the  ore  bodies  many  feet  below  the  surface. 

ORIGIN  OF  THE  ORE  BODIES. 

Information  concerning  the  copper  deposits  of  Prince  William 
Sound  is  far  from  complete.  There  are  only  two  producing  mines, 
and  to  only  one  of  these  have  the  writers  had  free  access.  At  the 
same  time  a considerable  body  of  information  concerning  these  ore 
deposits  is  at  hand,  and  this,  coupled  with  the  resemblance  of  these 
to  other,  better-known  deposits,  makes  it  possible  to  outline  a feasible 
explanation  for  the  origin  of  the  copper  deposits  of  the  sound. 

The  copper  veins  and  ore  bodies  are  found  either  in  or  in  close 
connection  with  basic  igneous  rocks.  An  exception  to  this  statement 
might  be  made  for  the  deposits  on  Latouche  Island,  but  even  here 
such  rocks  are  known  at  both  the  northeast  and  the  south  ends  of  the 
island,  and  a highly  sheared,  probably  igneous  rock  occurs  on  the 
property  of  the  Latouche  Copper  Mining  Company  a short  distance 
northeast  of  the  Bonanza  mine.  The  ores  occur  in  zones  along  which 
there  has  been  fracturing  or  shearing  or  both.  The  ore  minerals  are 
themselves  of  more  recent  date  than  most  of  this  fracturing  and 
shearing,  which  has  taken  place  during  or  after  the  last  folding  of 
the  rocks  of  the  Orca  group,  and  consequently  the  ore  deposits  are 
of  considerably  later  origin  than  most  of  the  basic  igneous  rocks  of 
the  district,  which  are  contemporaneous  with  the  Orca  sediments  and 
have  been  severely  affected  by  the  above-mentioned  dynamic  action. 
Other  basic  rocks  later  than  or  contemporary  with  the  fracturing 
and  shearing  are  not  always  clearly  recognizable.  Yet  a few  diabase 
dikes  are  known  which  do  not  seem  to  have  been  affected  by  dynamic 
metamorphism.  A dike  of  this  character  forms  the  long  island  on 
the  southwest  side  of  Tatitlek  Narrows,  and  this  dike  or  another  of 
the  same  nature  may  have  played  an  important  part  in  the  formation 
of  the  ore  body  of  the  Ellamar  mine.  In  fact,  fragments  of  coarse 
diabase  occur  on  the  beach  near  this  mine,  and  an  earlier  report 
speaks  of  a diabase  dike  at  the  mine.®  A few  small  unsheared  diabase 
dikes,  cutting  the  sediments  and  igneous  rocks  of  the  Orca  group, 
have  been  noted,  and  it  is  possible  that  the  gabbro  mass  on  the  north- 
east end  of  Latouche  Island  may  be  of  later  date  than  the  folding  of 
the  Orca  group.  There  is  thus  fairly  definite  proof  of  the  intrusion 
of  at  least  small  masses  of  igneous  rocks  at  a date  later  than  the  for- 


Harriman  Alaska  Expedition,  vol.  4,  1904,  p,  25. 


58  RECONNAISSANCE  OF  PRINCE  WILLIAM  SOUND,  ALASKA. 

Illation  and  folding  of  the  rocks  in  Avhich  the  ore  deposits  lie,  but 
the  relation  of  these  later  igneous  rocks  to  the  shearing  and  fracturing 
and  to  the  ore  deposits  themselves  is  not  definitely  known. 

The  minerals  in  the  ore  bodies  are  chiefly  pyrrhotite  and  chalco- 
pyrite.  With  these  in  places  are  quartz,  pyrite,  and  sphalerite,  and  in 
at  least  one  vein  magnetite  occurs.  As  a rule  the  ore  minerals  are 
intimately  intergrown  and  are  thus  apparently  of  contemporaneous 
origin. 

The  ore  bodies  occur  in  more  or  less  irregular  elongated  lenses 
which  widen  and  narrow  as  they  are  traced  along  the  strike  and  some 
of  which  pinch  out  entirely.  The  information  at  hand  shows  that 
they  vary  similarly  with  depth,  although  detailed  knowledge  of  most 
of  the  deposits  is  not  available. 

The  district  has  been  recently  glaciated  and  the  present  ground- 
water  level  is  close  to  the  surface.  The  weathered  parts  of  the  veins, 
if  there  were  such,  have  been  removed  by  glaciation  and  recent  weath- 
ering has  extended  a feAv  inches  or  a few  feet  below  the  surface. 
There  is  thus  lacking  a considerable  leached  zone  in  the  upper  part  of 
these  veins. 

The  facts  stated  above  lead  to  the  conclusion  that  the  ore  bodies 
were  probably  formed  under  somewhat  deep-seated  conditions  and 
i^robably  in  connection  with  the  intrusion  of  basic  igneous  rocks. 

An  alternative  hypothesis  for  the  origin  of  at  least  some  of  these 
ore  deposits  would  suggest  a primary  origin,  somewhat  similar  to 
that  outlined  above,  followed  by  secondary  enrichment  of  the  upper 
parts  of  the  veins  by  downward  percolating  surface  waters  before  the 
last  glaciation  of  the  district.  During  glaciation  the  upper  leached 
parts  of  the  veins  were  removed,  and  there  are  thus  left  to-day  the 
lower  parts  of  the  enriched  portions,  which  grade  downward  into  the 
leaner  nonenriched  primary  deposits.  Such  an  explanation  may 
apply  to  the  ore  at  some  of  the  prospects  near  Orca,  where  there  are 
considerably  larger  amounts  than  usual  of  secondary  minerals,  but 
no  information  is  at  hand  concerning  the  change  in  the  character  of 
these  deposits  with  depth.  A similar  explanation  may  apply  to  the 
deposit  at  the  Bonanza  mine,  where  the  ore  body  lies  on  and  just 
below  a steep  slope,  a favorable  topographic  situation  for  a second- 
arily enriched  deposit,  and  the  ore  itself  contains  much  more  chal- 
copyrite  and  much  less  pyrrhotite  than  usual;  in  fact,  much  of  the 
pyrrhotite  occurs  in  the  bands  of  practically  solid  sulphides  (men- 
tioned in  the  description  of  the  mine,  p.  66)  and  chalcopyrite  is  less 
abundant  in  the  lower  level  of  the  mine  than  it  is  nearer  the  surface. 
Since  glaciation  there  has  been  surface  leaching  (and  probable  en- 
richment) of  the  deposit,  as  is  shown  (1)  by  gossan  a few  feet  in 
thickness,  (2)  by  a zone  of  black  sulphides  a few  inches  in  thickness 


COPPER. 


59 


above  the  main  ore,  and  (3)  by  waters  which  are  carrying  copper  in 
solution  and  are  in  one  place  depositing  native  copper  and  malachite. 

SPECIAL  DESCRIPTIONS. 

There  are  nearly  200  copper  prospects  about  the  shores  of  Prince 
William  Sound.  At  many  of  these  practically  no  work  has  been 
done,  but  at  many  others  there  has  been  more  or  less  stripping,  dig- 
ging of  test  pits,  and  tunneling.  Most  of  the  prospects  on  which 
work  has  been  done  have  been  visited  during  the  progress  of  this 
investigation.  The  following  descriptions  are  confined  to  places 
where  considerable  development  work  has  been  carried  on  or  where 
features  of  special  interest  occur. 

GALENA  BAY. 

Several  prospects  are  located  on  the  north  slopes  of  Copper  Moun- 
tain, south  of  the  head  of  Galena  Bay.  At  one  of  these  localities, 
Vesuvius-  Valley,  there  has  been  much  activity,  the  principal  work 
being  on  one  long  tunnel.  This  was  worked  by  the  Prince  William 
Sound  Mining  Company  and  had  a length  of  over  300  feet  in  1905. 
This  property  was  later  taken  over  by  the  Galena  Bay  Mining  Com- 
pany, which  constructed  a dam  that  gives  a 52-foot  head  of  water 
and  installed  an  electric  power  plant.  The  electric  power  is  trans- 
mitted about  3 miles  southward  and  used  to  run  an  air  compressor  at 
the  mouth  of  the  above-mentioned  tunnel,  which  in  August,  1908,  had 
reached  a length  of  over  1,500  feet.  The  mouth  of  the  tunnel  is 
about  750  feet  above  sea  level,  and  it  is  being  driven  in  to  intersect  a 
large  shear  zone  which  outcrops  some  800  feet  above.  It  is  expected 
that  when  the  ore  zone  is  reached  an  aerial  wire-rope  tramway  will 
be  installed  from  the  tunnel  to  tide  water,  a distance  of  about  18,000 
feet.  The  material  for  this  tramway  was  on  the  ground  in  1908. 

In  1909  this  tunnel  was  extended  to  a length  of  1,800  feet  and  some 
diamond  drilling  was  done  from  the  breast  of  the  tunnel.  An  ore 
body  30  feet  in  thickness  and  200  feet  from  the  breast  of  the  tunnel, 
lying  probably  in  the  shear  zone  outcropping  above,  was  penetrated 
by  the  drills.  Further  drilling  was  done  on  the  Sunnyside  claim, 
about  3,000  feet  from  the  mouth  of  this  tunnel,  on  the  west  side  of 
Vesuvius  Valley.® 

ELLAMAR. 

The  Ellamar  mine  is  located  at  the  town  of  Ellamar,  on  the  east 
shore  of  Virgin  Bay.  (See  PI.  X,  A.)  The  writer  was  permitted 
to  enter  the  mine  only  in  September,  1905,  and  the  accompanying 


"Information  from  R.  C.  Bogue. 


60  RECONNAISSANCE  OF  PRINCE  WILLIAM  SOUND,  ALASKA. 


map  (fig.  4)  is  of  the  workings  at  that  date.  This  property  was 
staked  in  1897  and  has  been  making  regular  shipments  of  copper  ore 
for  several  years.  The  mine  has  been  opened  to  a depth  of  600  feet. 
The  ore  body  outcrops  at  the  surface  and  is  uncovered  at  low  tide. 
The  form  of  the  ore  body  is  lens-shaped,  with  its  major  axis  strik- 


ing N.  35°  W.  The  dip  is  80°  NE.  to  90°,  and  there  is  a pitch  of 
about  35°  toward  the  southeast.  The  ore  body  reaches  its  largest 
size  on  the  200-foot  level,  where  it  has  a length  of  190  feet  and  a 
width  of  80  feet.  (See  fig.  4.)  The  ore  body  consists  of  chalcopy- 
rite,  pyrite,  pyrrhotite,  and  country  rock.  Commonly  the  rock  is 
lacking  and  the  ore  body  is  practically  solid  sulphides.  The  high- 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  443  PLATE  X 


A.  ELLAMAR  MINE  AT  ELLAMAR,  JULY,  1908. 


B.  DOCK  AND  ORE  BUNKERS  OF  THE  STANDARD  COPPER  MINES  COMPANY  ON 
LANDLOCKED  BAY. 


Photograph  by  Cantwell. 


COPPER. 


61 


est-grade  ore  is  in  general  confined  to  a poorly  defined  ore  shoot 
which  forms  the  middle  of  the  foot  wall  half  of  the  ore  body.  The 
country  rock  is  soft  black  slate,  with  a few  bands  of  graywacke  and 
black  limestone.  The  strike  of  the  rocks  is  in  general  parallel  to 
that  of  the  ore  body.  Diabase  bowlders,  evidently  from  the  rock 
in  place  close  at  hand,  occur  150  feet  north  of  the  mine  and  a dia- 
base dike  has  been  reported  from  this  mine.®  The  black  slate  is  much 
fissured  and  crushed  and  the  fragments  are  commonly  slickensided. 
The  ore  is  in  the  main  massive  and  not  fractured,  although  there  are 
some  small  cracks  which  have  been  filled  by  calcite  and  quartz. 

During  the  summer  of  1009  and  part  of  1910  a horseshoe-shaped 
cotter  dam,  400  feet  in  length  and  20  feet  above  low  tide,  was  under 
construction  near  the  low-tide  line  at  the  Ellamar  mine,  the  object  of 
the  dam  being  to  exclude  the  high  tide  from  the  outcrop  of  the  ore 
body  so  that  the  part  of  this  body  between  the  100-foot  level  and  the 
surface  can  be  removed. 


BOULDER  BAY. 

Boulder  Bay  lies  just  west  of  Copper  Mountain  and  much  pros- 
pecting has  been  carried  on  near  its  head.  The  chief  work  has  been 
done  by  the  Reynolds- Alaska  Development  Company,  Avhich  has 
about  20  claims  east  of  the  head  of  the  bay.  The  property  is  devel- 
oped by  a wharf,  electric  plant,  air  compressor,  office  and  bunk 
houses,  supply  house,  superintendent’s  house,  and  about  2,100  feet 
of  drift,  in  the  main  tunnel  and  200  feet  of  drift  in  a smaller  opening. 
The  main  tunnel  is  at  tide  Avater  and  is  composed  of  a rather 
complicated  system  of  crosscuts,  winzes,  and  raises,  driven  through 
interbedded  greenstones,  slates,  and  grayAvackes.  It  is  lighted  by 
electricity  on  the  main  drifts.  A few  veins  of  chalcopyrite  Avere 
encountered.  About  150  feet  above  this  system  is  the  smaller  tunnel 
mentioned  above.  It  is  in  greenstone  having  locally  disseminated 
chalcopyrite  and  small  veins  of  the  same  mineral  also  occur.  Just 
to  the  right  of  the  main  adit  is  an  excavation,  from  Avhich,  it  Avas 
reported,  several  tons  of  shipping  ore  aa  ere  procured.  Several  hun- 
dred tons  of  ore  are  said  to  have  been  shipped  from  this  property. 
Some  of  this  ore  came  from  tAvo  large  boAvlders,  composed  chiefly  of 
iron  and  copper  sulphides,  Avhich  Avere  found  on  the  beach  at  the 
mouth  of  the  main  tunnel. 


LANDLOCKED  BAY. 

Much  prospecting  has  been  done  about  both  the  south  and  the 
north  shores  of  this  bay.  The  most  extensive  Avork  has  been  done 
on  the  north  shore  by  two  companies,  the  Standard  Copper  Mines 
Company. and  the  Three  Man  Mining  Company. 


Hari-iman  Alaska  Expedition,  vol.  4,  p.  25. 


62  RECONNAISSANCE  OF  PRINCE  WILLIAM  SOUND,  ALASKA. 

STANDARD  COPPER  MINES  COMPANY. 

The  Standard  company  has  constructed  a wharf,  ore  bunkers, 
office,  etc.,  on  the  north  side  of  Landlocked  Bay.  (See  PI.  X,  B^) 
From  the  wharf  a wire-rope  aerial  tramway,  2,526  feet  in  length, 
leads  up  the  south  side  of  Copper  Mountain.  Above  this  tramway 
is  another,  923  feet  long,  leading  to  the  mouth  of  a tunnel  some  2,000 
feet  above  sea  level.  This  tunnel  is  run  to  intercept  three  ore-bearing 
zones  that  outcrop  on  the  mountain  above.  In  August,  1908,  the 
tunnel  had  reached  a length  of  420  feet.  The  lowest  ore  zone  is  inter- 
sected near  the  mouth  of  the  tunnel,  and  from  this  several  hundred 
tons  of  ore  have  been  mined,  most  of  which  has  been  shipped.  The 
second  zone  is  not  clearly  cut  by  the  tunnel,  and  at  the  time  of  visit 
the  tunnel  was  thought  to  be  entering  the  third  zone.  These  zones 
are  schistose  areas  in  the  greenstone  of  Copper  Mountain  and  they 
carry  lens-shaped  bodies  of  ore.  The  property  has  also  been  developed 
by  several  smaller  tunnels  and  strippings. 

THREE  MAN  MINING  COMPANY. 

The  Three  Man  Company  has  a considerable  number  of  claims, 
locally  known  as  the  Dickey  claims,  about  the  head  of  Landlocked 
Bay.  Most  of  the  development  work  has  been  done  on  the  north  side 
of  the  bay,  where  numerous  tunnels  have  been  run,  strippings  made, 
and  several  veins  revealed.  Much  of  the  work  has  been  done  by 
drifting  along  the  veins  or  by  short  crosscuts  which  intersect  the 
veins.  The  veins  are  in  greenstone,  graywacke,  and  slate,  and  consist 
of  schistose  shear  zones  carrying  chalcopyrite  and  pyrrhotite.  Sev- 
eral of  these  shear  zones  give  good  examples  of  the  two  parts  into 
which  some  such  zones  are  divided — that  is,  there  is  a central  layer  of 
nearly  solid  sulphides,  outside  of  which  the  ore  is  disseminated 
through  the  sheared  rock.  Trial  shipments  have  been  made  from 
these  claims  and  more  ore  is  now  ready  for  shipment.  Most  of  the 
work  has,  however,  been  devoted  to  opening  the  veins  and  not  to  get- 
ting out  ore  for  shipment. 

FIDALGO  BAY. 

The  prospects  on  Fidalgo  Bay  were  discovered  at  a later  date  than 
most  of  the  other  prospects  on  the  sound,  and  these  discoveries  have 
considerably  extended  the  territory  in  which  the  search  for  copper 
is  actively  progressing. 

WHALEN  AND  NELSON  PROSPECT. 

On  the  south  side  of  Fidalgo  Bay,  T miles  east  of  Fish  Bay,  is  a 
smaller  bay  called  Whalen  Bay.  Two  miles  east  of  the  head  of 
Whalen  Bay  and  about  700  feet  above  sea  level  are  some  strippings 


COPPER. 


68 


and  a small  tunnel.  The  country  rock  is  a hard  black  to  greenish 
slate  and  the  ore  is  a hard  band  of  nonslaty  rock  containing  irregular 
stringers  and  disseminated  grains  of  chalcopyrite  and  pyrrhotite. 
This  band  of  ore  is  2 to  4 feet  in  thickness  where  examined  and  is 
reported  to  have  been  uncovered  at  intervals  for  a considerable  dis- 
tance, in  some  places  being  12  feet  thick. 

FIDALGO  MINING  COMPANY. 

The  prospect  owned  by  the  Fidalgo  Mining  Company  is  located  on 
the  south  side  of  Fidalgo  Bay,  a mile  southwest  of  Whalen  Bay. 
Twenty-four  claims,  locally  known  as  Blakney’s  prospect,  have  been 
staked.  A supply  house  at  the  beach,  a bunk  house,  and  a tunnel  are 
the  main  developments  on  this  property.  This  tunnel  is  2,800  feet 
from  the  shore  and  450  feet  in  length.  It  follows  a well-defined 
shear  zone.  Two  rather  definite  lens-shaped  ore  shoots,  each  about 
5 by  50  feet  in  cross  section,  have  been  struck  at  200  and  300  feet 
from  the  entrance,  and  many  small  stringers  of  ore,  which  is  chiefly 
chalcopyrite,  occur  throughout  the  tunnel.  A small  crosscut  beyond 
the  second  ore  shoot  shows  a 20-inch  vein  of  nearly  solid  chalcopyrite. 
Several  small  strippings  have  been  made  on  the  shear  zone,  which  has 
been  traced  for  about  3,000  feet.  Some  ore  is  ready  for  shipment. 

FIDALGO  ALASKA  COPPER  COMPANY. 

The  property  of  the  Fidalgo  Alaska  Copper  Company  is  on  the 
south  side  of  Fidalgo  Bay,  south  of  Fish  Bay  and  half  a mile  east 
of  Irish  Cove.  The  main  development  work  has  been  on  and  near 
the  top  of  a hill,  which  rises  about  1,000  feet  above  sea  level.  A large 
amount  of  stripping  has  been  done,  and  several  short  tunnels  and 
two  longer  ones  have  been  run.  The  main  tunnel  has  over  400  feet 
of  workings.  The  country  rock  is  a hard  black  to  gray  slate,  with  a 
little  graywacke.  The  ore,  which  is  chalcopyrite  with  a little  pyrite, 
is  in  hard,  fractured  zones  in  the  country  rock  and  occurs  as  a 
cement  to  the  fractures,  as  irregular  stringers,  as  disseminated  grains, 
and  as  larger  replacements  of  the  country  rock.  These  fractured 
zones  are  irregular  in  size  and  extent  and  some  of  them  have  proved 
not  to  continue  far.  Developments  have  not  yet  shown  how  extensive 
others  of  these  zones  are.  Altogether  there  is  a considerable  amount 
of  ore  exposed  in  the  strippings  and  in  the  tunnels,  and  some  ore  is 
ready  for  shipment. 

LATOUCHE  ISLAND. 

BONANZA  MINE. 

A trial  shipment  of  about  a ton  of  ore  was  made  from  the  Bonanza 
mine  in  1899.  Other  small  shipments  followed  and  in  1903  over  a 
hundred  tons  was  shipped.  Kegular  shipments  began  in  1904  and 
58668°— Bull.  443—10 5 


64  EECONNAISSANCE  OF  PRINCE  WILLIAM  SOUND,  ALASKA. 


have  continued  since.  A dock,  ore  bunkers,  an  office,  and  mess  and 
bunk  houses  have  been  constructed  (PL  XI,  B)^  and  two  tramways 
have  been  built  from  the  dock  to  the  mine,  about  half  a mile  distant. 
The  mine  is  in  the  main  a large  open  hill  face  (PL  XI,  A),  from 
which  the  ore  is  quarried  and  run  down  to  two  tunnels,  one  30  and 
the  other  120  feet  below  the  quarry  floor.  The  ore  is  trammed  from 
these  tunnels  to  the  dock.  Aside  from  the  open  quarry  about  4,000 
feet  of  tunneling  had  been  done  on  the  property  up  to  the  end  of 
1909.  The  shape  and  size  of  the  quarry  is  shown  in  figure  5,  and  the 
two  tunnels  in  figure  6. 

The  country  rocks  at  the  Bonanza  mine  are  slates  and  graywackes 
(see  PL  XII  and  fig.  3),  the  slates  being  more  common  west  of  the 
mine  and  the  graywackes  more  common  in  the  bold  hill  east  of  the 
mine.  Some  of  the  graywackes  are  slightly  calcareous  and  small 


VERTICAL  AND  HORIZONTAL  SCALE 


PLAN 

Figukk  5. — Bonanza  mine,  Latouche  Island,  a.  Sketch  plan  of  the  quarry ; h,  sketch 

section  of  the  quarry. 


calcite  veins  occur  in  a few  places.  At  the  mine  itself  the  country 
rock  is  in  very  large  part  a white-weathering,  very  fine  grained, 
dense,  hard  greenish  flinty  rock.  This  rock  is  composed,  as  seen 
under  the  microscope,  of  quartz  and  a chloritic  mineral  (probably 
ripidolite)  with  small  amounts  of  a fresh  acidic  plagioclase.  A 
chemical  analysis  of  this  flinty  rock  gave  the  results  shown  in  the 
accompanying  table.  In  this  analysis  the  ferrous  iron,  magnesia, 
water  above  100°,  and  most  of  the  alumina  are  to  be  referred  to  the 
chloritic  mineral;  the  feldspar  is  small  in  amount;  and  the  main 
part  of  the  rock  is  quartz.  No  certainly  clastic  grains  are  seen  in 
the  sections,  and  in  the  field  no  banding  or  bedding  was  noted  in 
this  flinty  rock,  and  its  relation  to  the  adjacent  slates  and  gray- 
wackes was  not  clear.  It  has  somewhat  the  appearance  of  an 
igneous  rock,  but  its  chemical  composition  is  not  similar  to  that  of 
anA^  known  igneous  rock. 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  443  PLATE  XI 


A.  QUARRY  FACE  OF  THE  BONANZA  MINE  ON  LATOUCHE  ISLAND,  JULY,  1908. 


B.  DOCK  AND  ORE  BUNKERS  OF  THE  BONANZA  MINE  ON  LATOUCHE  ISLAND,  JULY,  1908. 


COPPER. 


65 


Figure  (>. — IMan  of  underground  workings  at  the  Bonanza  mine,  .Tune,  1909. 


Chemical  anali/.si.s  of  fUntu  >'ock  from  the  Bonanza  mine,  Latonehe  Island. 

[By  R.  C.  Wells.] 


Si02 79.  40 

f Ti02 . 33 

$ AI2O3 - 6. 11 

Sr  Fe203 . 16 

FeO___^ 5. 18 

I MgO 4. 13 

r MnO .15 

K20___ .19 

Na20 . 42 

,,  H2O— . 15 

H2O  + 2.75 


FeS. 0.  SO 

FeCuS2 . 72 


Cu__ 

Ni__. 

Co__. 

P2O5- 

C02_ 

Zr02. 

BaO. 

F___ 


100.  28 


i 8 8 8 8 8 8 S 


66  RECONNAISSANCE  OF  PRINCE  WILLIAM  SOUND,  ALASKA. 

The  ore  of  the  Bonanza  mine  is  chiefly  chalcopyrite.  This  occurs 
in  fractures  and  as  replacements  of  the  country  rock,  which  in  large 
part  is  the  greenish  flinty  rock  already  described.  Ore  occurs  to  a 
less  extent  in  the  graywackes  and  slates,  and  the  flinty  rock  does  not 
everywhere  carry  ore.  The  distribution  of  this  flinty  rock  is  shoAvn 
in  figure  6.  The  ore  is  not  so  widespread  as  this  rock  in  the  lower 
level,  but  in  the  upper  level  the  distribution  of  the  ore  and  that  of 
the  flinty  rock  are  more  nearly  coincident. 

In  addition  to  the  ore  noted  above  there  are  10-foot  bands  of  prac- 
tically solid  sulphides  (pyrrhotite,  pyrite,  and  chalcopyrite).  One 
of  these  outcrops  in  the  creek  just  west  of  the  mine,  another  is  cut  in 
the  upper  level  at  the  southwestern  part  of  the  mine,  and  still  another 

occurs  in  the  lower  level  at  the 
northwestern  part  of  the  mine. 
Whether  these  bands  are  dis- 
tinct from  one  another  or 
whether  they  represent  really 
only  one  band  is  not  known. 
The  solid  sulphide  bands  cut 
in  the  workings  strike  north 
or  a few  degrees  west  of  north 
and  dip  60°  to  70°  W.  The 
general  strike  and  dip  of  the 
bedding,  as  shown  in  the 
slates  and  graywackes,  are 
approximately  parallel  with 
those  of  the  sulphide  bands. 

In  the  mine  workings  are  a 
number  of  faults,  a few  of 
which  are  shown  in  figure  6. 
Some  of  these  are  thrust 
faults;  others  are  not  clearly  determinable.  At  least  some  of  the 
faults  are  later  than  the  ore  deposition. 

In  1910  ore  bunkers  having  a capacity  of  1,500  tons  were  built  at  the 
Bonanza  mine,  a small  water-power  plant  was  installed,  and  prospect- 
ing by  use  of  the  diamond  drill  was  undertaken. 

REYNOLDS-ALASKA  DEVELOPMENT  COMPANY. 

On  Horseshoe  Bay  the  Eeynolds-Alaska  Development  Company 
has  built  a small  town,  installed  a pipe  line  and  electric  power  plant, 
and  constructed  over  a mile  of  corduroy  road  from  its  dock  eastward 
to  its  shaft  and  tunnels.  The  shaft,  reported  to  be  100  feet  deep  with 
a crosscut  at  its  bottom  to  an  ore  body,  was  full  of  water  at  the  time 
of  visit.  About  half  a mile  northeast  of  the  shaft  and  400  feet  above 


Figure  7, — Map  of  tunnels  and  ore  body  on  the 
Duchess  claim  of  the  Reynolds-Alaska  Devel- 
opment Company,  Latouche  Island. 


COPPER. 


67 


sea  level  some  2,000  feet  of  tunneling  has  been  done,  most  of  which 
is  on  the  Duchess  claim.  Here  a lens-shaped  body  of  ore  has  been 
encountered  which  strikes  northeasterly  and  dips  70°  W.  (See  fig. 
7.)  It  is  only  a few  inches  in  thickness  where  first  encountered  at 
the  south-southwest,  but  thickens  gradually  northward  for  500  feet 
along  the  strike,  reaching  a thickness  of  45  feet  at  the  point  to  which 
exploration  has  gone.  The  ore  body  consists  of  pyrite  and  some  chal- 
copyrite  mixed  with  bands  of  slate  and  graywacke.  Several  hun- 
dred tons  of  sorted  ore  are  on  the  dump,  and  shipments  are  reported 
to  have  been  made  from  this  tunnel. 

LATOUCHE  COPPER  MINING  COMPANY. 

The  property  of  the  Latouche  Copper  Mining  Company  is  situated 
about  half  a niile  north  of  the  Bonanza  mine.  A dock,  ore  bunkers, 
mess  houses,  and  a tramway  from  the  dock  to  the  tunnel,  a distance  of 
a quarter  of  a mile,  have  been  built.  The  property  has  been  devel- 
oped by  numerous  shallow  pits  and  trenches  and  by  a 700-foot  tunnel 
which  strikes  the  ore-bearing  ground  200  feet  below  the  surface.  The 
ore  is  rock  charged  with  chalcopyrite  and  some  pyrrhotite  and  pyrite. 
Most  of  the  ore  removed  has  come  from  one  stope,  Avhich  is  45  by  15 
feet  in  area  and  5 to  10  feet  in  height.  Several  hundred  tons  of  ore 
was  shipped  in  1907,  and  there  is  some  ore  remaining  in  the  bunkers. 
A boiler  and  an  air  compressor  were  purchased  for  this  mine  in  1909. 

KNIGHT  ISLAND. 

A large  amount  of  prospecting  was  done  on  Knight  Island  in  1906 
and  1907,  and  much  of  this  was  carried  on  near  Drier  Bay,  on  the 
Avest  side  of  the  island.  Only  a few  of  the  prospects  are  described 
below. 

KNIGHTS  ISLAND  CONSOLIDATED  COPPER  COMPANY. 

The  Knights  Island  Consolidated  Copper  Company,  locally  known 
as  the  Hubbard-Elliott  Company,  has  installed  a wharf,  offices,  ore 
bunkers,  and  steam-power  plant  at  the  northeast  corner  of  Drier 
Bay.  Work  has  been  done  on  a number  of  claims,  but  the  main 
development  has  been  on  two  tunnels  called  the  Monarch  and  the 
Bald  Eagle.  The  former  is  1^  miles  northeast  of  the  dock  and  about 
600  feet  above  the  sea.  Here  some  350  feet  of  development  work  has 
been  done.  The  Bald  Eagle  tunnel  is  about  900  feet  above  sea  level 
and  three-fourths  of  a mile  northeast  of  the  dock.  Here  is  a north- 
AvestAvard- facing  cliff  Avith  an  iron-stained  surface.  The  rock  is  green- 
stone Avith  irregular  schistose  zones  Avhich  Avrap  around  masses  of  non- 
schistose  rock.  The  schistose  zones  carry  chalcopyrite  and  pyrrho- 


68  RECONNAISSANCE  OF  PRINCE  WILLIAM  SOUND,  ALASKA. 

tite,  and  in  some  of  the  zones  these  sulphides  are  abundant  and  form 
ore  bodies,  from  one  of  which  a few  hundred  tons  of  ore  has  been 
mined.  (See  fig.  8.)  Connecting  the  Bald  Eagle  tunnel  with  the 
dock  is  a wire-rope  aerial  tramway,  the  upper  station  of  Avhich  was 
unfortunately  somewhat  damaged  by  a snow  slide  in  the  early  part 
of  1908.  Shipments  of  ore  have  been  made  from  this  tunnel,  and  some 
ore  remains  in  the  ore  bunkers. 

RUSSELL  BALL  COPPER  COMPANY. 

The  prospect  of  the  Russell  Ball  Copper  Company  is  located  on 
the  south  side  of  Drier  Bay,  between  Barnes  Cove  and  Mallard  Bay. 

The  company  has  located  six 
claims,  four  on  Drier  Bay  and 
two  over  the  ridge  from  Drier 
Bay  toward  Snug  Harbor. 
The  property  on  Drier  Bay  is 
developed  by  four  openings. 
A wire-rope  aerial  tram  oper- 
ated by  a windlass  has  been 
rigged  from  the  upper  tunnel 
to  the  shore.  This  tunnel  is 
520  feet  above  sea  level  and  is 
00  feet  long  upon  a vein  of 
nearly  solid  chalcopyrite  with 
a little  pyrrhotite.  Good  out- 
croppings are  reported  to  be 
above  at  an  altitude  of  about 
1,000  feet,  but  these  were  cov- 
ered with  snow  when  visited 
in  July,  1908.  The  other  three 
openings  are  below,  and  range 
from  12  to  30  feet  in  length. 
They  are  intended  to  cut  the 
vein  mentioned  above,  but  are 
not  driven  far  enough  to  strike 
it.  Some  ore  is  sacked  ready  for  shipment,  and  a small  shipment 
was  made  in  July,  1908. 

HAPPY  JACK  COPPER  MINING  AND  DEVELOPMENT  COMPANY. 

The  Happy  Jack  Copper  Mining  and  Development  Company’s 
property  is  located  on  the  south  side  of  Hogan  Bay,  Knight  Island, 
just  at  the  entrance.  A steam  plant,  an  office,  and  mess  and  bunk 
houses  have  been  constructed.  The  main  work  has  been  on  a tunnel 
at  the  shore.  In  July,  1908,  this  tunnel  had  reached  a length  of  986 


the  Bald  Eagle  claim  of  the  Knights  Island 
Consolidated  Copper  Company,  Knight  Island. 


COPPER. 


(59 


feet.  It  is  being  rim  to  intersect  a vein  which  outcrops  higher  up 
and  to  the  southeast.  This  vein  extends  along  a fissure,  cutting  across 
the  strike  of  the  country  rocks,  which  are  slates,  graywackes,  and 
greenstones.  The  vein,  where  examined,  varies  from  1 to  4 feet  in 
thickness  and  contains  quartz,  chalcopyrite,  and  pyrrhotite.  Two 
tunnels  have  been  run  on  this  vein,  one  398  feet  and  the  other  535 
feet  above  sea  level.  The  upper  tunnel  is  85  feet  in  length,  and  the 
other,  with  its  branches,  about  450  feet.  Several  tons  of  ore  are  now 
on  the  dumps  from  these  two  tunnels  and  some  ore  has  been  shipped. 

COPPER  BULLION  CLAIMS. 

The  Copper  Bullion  claims,  commonly  known  as  Rua's  claims,  are 
situated  on  the  east  side  of  Knight  Island,  and  the  development  work 
consists  of  a tunnel,  which  had  reached  a length  of  360  feet  in  July, 
1908.  This  tunnel  is  about  half  a mile  from  the  east  shore  of  the 
island  and  miles  north  of  the  entrance  to  Marsha  Harbor.  The 
rock  excavated  in  the  tunnel  is  greenstone  with  a few  stringers  of 
pyrrhotite  and  chalcopyrite,  but  at  the  end  a brecciated  zone,  cemented 
by  quartz  and  these  two  sulphides,  has  been  encountered.  So  far  as 
the  Avorkings  show,  this  zone  is  about 
60  feet  in  width  and  strikes  in  a 
northeasterly  direction.  Some  400 
feet  above  this  tunnel,  at  the  base  of 
a southward-facing  cliff  on  the  south 
side  of  Iron  Mountain,  is  an  exposure 
of  ore  65  feet  in  Avidth.  All  of  this 
width,  except  about  10  feet  of  mixed 
ore  and  rock,  is  practically  solid  pyr- 
rhotite with  a small  percentage  of 
chalcop3^rite.  About  200  feet  farther 
up  the  cliff  the  ore  body  appears  to  be  30  feet  in  Avidth,  and  at  the 
top  of  the  ridge,  150  feet  still  higher,  there  is  reported  to  be  12  feet 
of  ore.  It  seems  probable  that  the  tunnel  cuts  this  same  ore  body. 

KNIGHTS  ISLAND  MINING  AND  DEVELOPMENT  COMPANY. 

At  the  head  of  Louis  Bay,  at  the  north  end  of  Knight  Island,  the 
Knights  Island  Mining  and  Development  Company  has  installed  a 
small  saAvmill  and  an  electric  plant.  From  this  plant  electric  drills 
have  been  worked  in  two  tunnels  miles  south  of  the  south  end  of 
this  bay.  One  of  these  tunnels  is  85  feet  in  length  and  cuts  five  schis- 
tose zones  2 to  18  inches  in  width,  in  greenstone.  (See  fig.  9.)  These 
zones  carry  pyrite,  chalcopyrite,  and  pyrrhotite.  The  main  or  lower 
tunnel  was  started  to  intersect  these  and  several  other  ore-bearing 


^ , 9 ^FEET 

Figure  9. — Tunnel  cutting  five  schis- 
tose ore-bearing  zones,  on  property 
of  Knights  Island  Mining  and  De- 
velopment Company,  near  north  end 
of  Knight  Island. 


70  RECONNAISSANCE  OF  PRINCE  WILLIAM  SOUND,  ALASKA. 

schistose  zones,  and  is  IGO  feet  in  length.  This  company  is  con- 
structing a small  sawmill,  to  be  run  by  water  power. 

ORCA  INLET. 

In  the  vicinity  of  Orca  Inlet,  and  especially  to  the  east  of  the 
inlet,  there  are  a number  of  copper  prospects,  but  little  work  has  been 
done  on  most  of  them.  The  Cordova  Copper  Company  ha-s  done  con- 
siderable prospecting  on  its  claims  between  Cordova  and  Orca.  The 
country  rocks  here  are  basic  amygdaloids,  Avhich  have  been  altered 
and  irregularly  fractured.  In  some  of  the  fractures  are  copper  ores, 
consisting  of  chalcopyrite,  chalcocite,  bornite,  native  copper,  cuprite, 
and  malachite.  Specimens  of  native  copper  from  this  place  were  on 
exhibit  at  the  Alaska-Yukon-Pacific  Exposition. 

In  1909  the  Cordova-Tacoma  Copper  Company  did  some  develop- 
ment work  on  its  Head-of-the-Bay  prospect,  2^  miles  east  of  the 
north  end  of  Cordova  Bay.  This  prospect  is  situated  near  the  con- 
tact of  the  country  black  slates  and  a mass  of  diorite. 

About  10  miles  northeast  of  Orca,  near  the  Scott  Glacier,  pros- 
pectors have  located  some  claims  on  veins  carrying  native  copper. 

SUMMARY. 

Present  developments  of  the  copper-mining  industry  on  Prince 
William  Sound  have  demonstrated  the  existence  of  two  ore  deposits 
of  commercial  importance,  that  of  the  Ellamar  mine  and  that  of  the 
Bonanza  mine.  The  size  of  the  former  is  known,  but  the  size  of  the 
Bonanza  deposit  is  unknown,  though  a large  tonnage  of  ore  is  already 
revealed.  There  are,  however,  other  properties  on  which  develop- 
ment work  has  not  yet  gone  far  enough  to  establish  conclusively 
their  economic  importance,  but  about  which  enough  is  known  to 
encourage  further  careful  prospecting.  The  location  of  some  of 
these  properties  is  at  or  close  to  tide  water,  and  the  present  demand 
for  ores  of  this  character  for  furnace  mixtures  makes  it  a matter 
of  reasonable  expectation  that  other  properties  than  the  two  men- 
tioned above  will  become  regularly  shipping  mines.  This  expecta- 
tion will  be  more  fully  realized  should  the  price  of  copper  advance 
or  should  the  opening  of  the  copper  mines  of  the  Copper  River  dis- 
trict and  the  opening  of  the  Bering  River  or  the  Matanuska  coal 
field  make  it  feasible  to  establish  plants  for  the  smelting  of  copper 
ores  on  Prince  William  Sound. 

PROSPECTING. 

In  prospecting  it  is  a good  rule  to  follow  the  ore  when  it  is  found. 
Moreover,  a certain  amount  of  money  spent  in  surface  strippings 


GOLD. 


71 


and  in  test  pits  and  tunnels  on  the  ore  will  usually  show  much  more 
concerning  the  value  of  an  ore  body  than  the  same  amount  spent  in 
deep  underground  workings.  The  ore  bodies  of  the  sound  vary  con- 
siderably in  thickness  and  in  metallic  content  in  a horizontal  direc- 
tion, locally  pinching  out  entirely;  and  fully  as  much,  if  not  more, 
variation  may  be  expected  in  depth.  It  is  not  good  practice  to  drive 
long  tunnels  to  intercept  ore  bodies  at  distances  of  a few  hundred 
feet  from  the  surface,  until  the  general  extent  and  character  of  the 
body  has  been  pretty  fully  ascertained  by  other  explorations.  Where 
a vein  or  a lens-shaped  body  pinches  out  it  may  be  well  worth  while 
to  conduct  explorations  for  a continuation  of  the  vein  or  for  another 
lens  of  ore  along  the  strike  of  the  first  one. 

Under  present  conditions  a prospect  to  be  encouraging  ought  to 
show  fair  promise  of  several  thousand  tons  of  ore  which  will  run  at 
least  4 per  cent  in  copjier  or,  if  less,  enough  gold  and  silver  to  coun- 
terbalance the  deficiency.  Under  more  favorable  conditions  than 
the  present  it  will  be  possible  to  mine  at  a profit  ore  running  less 
than  4 per  cent  in  copper,  especially  if  large  bodies  of  low-grade  ore 
are  discovered. 

GOLD. 

The  copper  ores  which  have  been  shipped  from  Prince  William 
Sound  all  carry  some  gold.  Peturns  from  available  assays  of  these 
ores  show  from  25  cents  to  $4.80  in  gold  to  the  ton  of  ore.  Figures 
for  the  average  gold  content  are  not  available,  but  it  is  estimated  that 
it  is  about  $1  a ton. 

PLACER  GOU). 

Prospecting  for  placer  gold  has  been  carried  on  along  a few  of  the 
streams  entering  the  sound,  such  as  Mineral  and  Gold  creeks,  on  the 
north  shore  of  Port  Valdez,  streams  entering  the  bay  in  which  is  the 
Shoup  Glacier,  and  Kings  River,  at  the  head  of  Port  Nellie  Juan. 
Work  in  these  places  was  carried  on  in  a small  way  and  returns  of  a 
few  dollars  per  day  per  man  have  been  reported.  A few  years  ago 
some  extensive  placer  mining  was  planned  for  the  upper  part  of  the 
stream  which  enters  Port  Valdez  in  Solomon  Gulch,  but  was  not 
carried  to  completion. 

GOLD-REARIXG  VEINS. 

In  connection  with  copper  prospecting  a few  quartz  veins  have 
been  encountered,  as  on  Glacier  Island  and  on  the  northwest  slope 
of  Copper  Mountain,  and  these  have  been  prospected  for  gold.  Two 
assays  have  been  made  from  these  veins,  one  from  the  decomposed 
upper  part  of  the  vein  and  the  other  from  the  unaltered  vein  material 
15  feet  below  the  surface.  These  assays  showed  traces  of  gold  and 
less  than  an  ounce  of  silver  per  ton. 


72  RECONNAISSANCE  OF  PRINCE  WILLIAM  SOUND,  ALASKA. 


Prospecting  of  gold-bearing  veins  has  been  carried  on  to  a small 
extent  in  a few  places  about  Prince  William  Sound.  One  of  these 
is  just  north  of  the  entrance  to  Fidalgo  Bay,  where  a quartz  vein 
occurs  in  black  slate.  No  assays  from  this  vein  are  available. 
Another  place  is  one-fourth  mile  south  of  the  east  side  of  the  front 
of  the  Barry  Glacier,  on  Port  Wells,  where  there  are  two  gray  aplite 
dikes  a few  feet  in  width.  Practically  no  work  has  been  done  here, 
but  assays  of  this  dike  material  are  reported  to  have  shoAvn  $2.35 
and  $2.85  in  gold  to  the  ton. 

More  extensive  prospecting,  with  encouraging  results,  has  been 
carried  on  near  McKinley  Lake  east  of  Cordova,  on  the  north  shore 
of  Port  Valdez,  and  on  Jackpot  Bay.  These  localities  are  described 
below. 

PORT  VALDEZ. 

By  Alfrp:o  II.  BEiOOKS. 

General  deseription. — Gold  was  first  found  near  Port  Valdez  in 
the  gravels  at  the  mouth  of  Mineral  Creek,  where  a little  sluicing 
was  done  in  1894.  In  1898  some  placer  claims  were  staked  on 
Solomon  Gulch,  on  the  south  side  of  Valdez  Inlet,  and  a little  sluic- 
ing was  attemj)ted.  Colors  of  gold  appear  to  be  widely  distributed 
in  the  alluvium  of  the  region,  but  no  workable  2)lacers  have  been 
found.  Most  of  the  streams  are  small  and  contain  only  a small 
amount  of  gravel. 

Small  auriferous  quartz  veins  have  long  been  known  to  occur  on 
Prince  William  Sound,  but  in  1909,  Avhen  the  Cliff  vein  was  dis- 
covered, none  had  been  developed  Avhich  gave  assurance  of  being  a 
Avorkable  deposit.  The  success  of  the  Cliff  mine,  which  has  been 
])roductiA"e  since  April,  1910,  has  greatly  stimulated  prospecting,  and 
in  1910  many  locations  Avere  made  in  the  Valdez  Inlet  region,  notably 
along  the  Avatersheds  of  Gold  and  Mineral  creeks.  The  folloAving 
notes  are  based  on  a A^ery  hasty  Ausit  paid  to  the  Cliff  mine  in  August, 
1910,  and  on  information  gathered  from  published  reports  and  from 
prospectors. 

The  bed  rock  along  the  inlet  appears  to  be  chiefly  slates  and  gray- 
Avackes  of  the  Valdez  group.  In  places  these  rocks  are  schistose  and 
some  of  the  slates  are  graphitic.  Schrader®  found  some  aplite  dikes 
near  Valdez.  The  general  strike  of  the  sediments  is  about  east  and 
Avest,  parallel  to  the  axis  of  Port  Valdez.  According  to  Mr.  Grant 
the  rocks  on  the  south  side  of  the  port  are  closely  folded  and  over- 
turned to  the  south.  On  the  north,  so  far  as  I could  see,  the  rocks 
are  also  closely  folded  and  someAvhat  faulted,  and  the  dips  are  pre- 
vailingl}^  to  the  north. 

® Schrader,  F.  C.,  A reconnaissance  of  a part  of  Prince  William  Sound  and  the  Copper 
River  district,  Alaska,  in  1898  ; Twentieth  Ann.  Kept,  U.  S.  Geol.  Survey,  pt.  7,  1900, 
p.  409. 


73 


GOLD. 

Where  examined,  the  rocks  showed  a well-developed  slaty  cleavage 
parallel  to  the  bedding.  There  appears  to  be  a marked  system  of 
jointing  which  crosses  the  foliation  nearly  at  right  angles.  The  sys- 
tem finds  expression  in  the  topography,  as  it  marks  lines  of  weakness 
to  erosional  agencies.  Gulches  of  marked  regularity  and  parallelism 
are  seen  on  the  mountain  side  north  of  Port  Valdez.  It  appears,  so 
far  as  can  be  seen  from  the  bay,  that  a number  of  the  veins  which 
have  been  opened  follow  this  system  of  jointing.  Prospectors,  how- 
ever, report  that  veins  are  found  which  run  in  various  directions. 
These  may,  however,  be  quartz  stringers  and  veins  that  follow  the 
foliation  and  probably  belong  to  a different  system  of  fractures  than 
that  of  the  Cliff  vein.  One  prospector  told  me  that  at  the  entrance  of 
Valdez  Bay,  west  of  Shoup  Bay,  the  quartz  veins  ran  directly  into 
the  mountain,  crossing  the  foliation  at  an  angle  of  about  15°.  These 
veins,  though  they  carry  gold,  are  not  known  to  be  of  commercial 
value.  It  is  asserted  that  the  extension  of  the  Cliff  vein  has  been 
found  on  the  Shoup  Bay  side,  but  that  it  takes  a turn  in  the  mountain 
to  the  northeast.  There  is  no  direct  evidence  of  this,  and  on  the  Port 
Valdez  side  the  fissuring  would  appear  to  be  remarkably  regular. 

The  Cliff  mine. — The  Cliff'  mine,  which  is  about  8 miles  from  Val- 
dez, is  located  at  the  east  end  of  the  bluff'  which  marks  the  limit  of  the 
gravel  bar  at  the  east  entrance  of  Shoup  Bay.  The  claim  was  staked 
in  1909 ( ?) , development  work  began  in  July,  1909,  and  a 3-stamp  mill, 
said  to  have  a capacity  of  30  tons  a day,  Avas  installed  in  April,  1910. 
As,  however,  up  to  the  time  of  my  visit  (iVugust,  1910)  only  one  con- 
centrating table  was  in  use,  the  mill  had  been  run  only  two  shifts 
(16  hours). 

The  country  rock  at  the  mine  appears  to  be  chiefly  dark  siliceous 
slate,  locally  graphitic  and  usually  blocky.  At  the  beach  the  strike 
is  about  east  and  Avest  and  the  dip  20°  to  30°  N.  The  slate  carries 
mica  ,and  is  in  places  heavily  charged  Avith  finely  divided  pyrite, 
Avhich  occurs  in  A^einlets  cutting  the  foliation  and  is  also  disseminated 
especially  along  the  cleavage  planes.  There  has  been  movement  later 
than  the  formation  of  the  pyrite,  as  is  shoAvn  by  slickensided  surfaces 
about  parallel  to  the  cleavages. 

The  vein  cuts  across  the  foliation  of  phyllites  Avith  a strike  of  about 
N.  30°  to  45°  W.,  averaging  about  N.  35°  W.  It  dips  to  the  south- 
Avest  at  an  angle  of  about  50°-T0°  but  has  some  rolls  in  it.  The  foot 
wall  is  smooth  and  along  it  there  is  from  half  an  inch  to  3 inches  of 
gouge  which  carries  values.  There  seems  to  have  been  no  movement 
along  the  hanging  Avail,  but  it  is  Avell  defined.  The  vein  ranges  in 
Avidth  from,  say,  an  inch,  where  quartz  may  be  entirely  lacking,  to  34 
inches.  The  managers  report  that  small  SAvellings  occur,  Avhere  the 
vein  widens  to  3 and  4^  feet.  The  vein  matter  is  in  places  entirely 
lacking,  but  the  fissure  is  everywhere  well  defined.  In  one  place  in 


74  RECONNAISSANCE  OF  PRINCE  WILLIAM  SOUND,  ALASKA. 

the  upper  tunnel  a roll  was  encountered  where  a bulge  in  the  foot  wall 
gave  a reverse  dip  to  the  vein.  On  the  whole,  the  strike  of  the  vein 
is  fairly  uniform  in  direction,  though  the  workings  show  minor 
swings  of  5°  to  10°.  At  an  upper  prospect  tunnel,  about  150  to  200 
feet  above  the  beach,  what  appears  to  be  the  same  vein  has  a thickness 
of  about  a foot.  So  far  as  determined  by  the  exposures,  the.  vein  is 
definitely  recognizable  for  about  300  to  400  feet,  but  the  managers 
stated  that  it  has  been  traced  by  float  throughout  the  length  of  the 
claim,  and  it  is  reported  that  the  same  vein  has  been  found  on  the 
north  side  of  the  ridge,  3,000  feet  from  the  mine. 

The  typical  vein  filling  is  a blue  quartz  carrying  considerable 
finely  disseminated  pyrite  and  also  apparently  minute  quantities  of 
arsenopyrite  and  galena,  but  no  detailed  study  of  the  ore  has  been 
made.  Visible  free  gold  is  found,  especially  in  the  upper  workings, 
where  there  has  been  considerable  oxidation.  Free  gold  also  occurs, 
however,  in  the  fresh  unaltered  vein  material,  where  it  is  clearly  not 
the  product  of  alteration.  In  places  the  ore  shows  a rough  banding, 
and  this  type  is  reported  to  carry  the  highest  values.  Some  of  the 
vein  material  is  crushed  and  some  shows  a suggestion  of  brecciation 
and  recementation. 

Much  of  the  ore  is  very  rich,  and  the  average  recovery  of  free  gold 
is  reported  to  be  about  $50  to  the  ton.  The  concentrates  are  said  to 
run  about  7 per  cent,  and  have  a value  of  about  $100  a ton  in  gold. 

Oxidation  of  vein  matter  is  very  marked  on  the  upper  level,  and 
was  observed  to  a distance  of  about  100  feet  from  the  entrance  of 
the  adit  on  the  lower  level.  Beyond  100  feet  on  the  lower  adit  there 
was  no  evidence  of  oxidation.  The  superintendent,  Mr.  Ray  Millard, 
stated  to  me  that  there  was  no  diminution  in  free-gold  values  with 
increase  in  depth.  At  the  same  time,  the  richest  specimens  of  free 
gold  seem  to  have  been  taken  from  the  upper  part  of  the  mine. 
Values  of  $1.50  to  $6  are  reported  in  the  hanging-wall  rock,  in 
which  many  quartz  stringers  were  observed  extending  a foot  or 
more  from  the  vein.  In  the  upper  adit  the  vein  matter  is  absent 
for  the  last  50  feet,  but  the  fissure  is  traceable.  It  is  in  this  part  of 
the  mine  that  the  roll  occurs. 

There  are  two  adit  tunnels  (which  are  connected  by  raises)  54 
feet  apart,  and  one  intermediate  drift.  Plans  are  made  for  sinking 
on  the  vein  in  the  lower  tunnel.  The  lower  adit  is  about  200  feet 
long. 

Other  j)Tospects. — There  are  a number  of  prospects  along  the  shore 
of  the  bay  between  the  Cliff  mine  and  Valdez.  I did  not  have  time 
to  examine  these,  but  they  appear  to  follow  fissures  which  parallel 
those  of  the  Cliff  mine.  Some  work  has  been  done  on  several  of 
these.  At  the  Imperial  an  adit  tunnel  has  been  driven  from  a point 
near  sea  level  along  the  vein  for  a distance  of  over  100  feet,  and  an 


GOLD. 


75 


air  compressor  is  being  installed.  A number  of  other  prospects  have 
also  been  located  on  Gold  Creek,  Mineral  Gulch,  and  Mineral  Moun- 
tain, and  many  of  these  have  yielded  specimens  sho^ving  free  gold. 
From  current  reports,  many  of  these  prospects  appear  to  be  mere 
stringers,  but  several  are  reported  to  be  large  enough  to  warrant  fur- 
ther exploration.  Development  work  is  being  actively  pushed  on  a 
number  of  them. 

Summary. — The  facts  in  hand  appear  to  justify  the  opinion  that 
auriferous  quartz  veining  is  not  uncommon  in  the  region  adjacent  to 
Valdez  Inlet.  The  facts  noted  at  the  Cliff  property  and  the  reports 
of  prospectors  seem  to  warrant  the  conclusion  that  other  auriferous 
veins  will  be  found  which  can  be  profitably  exploited.  The  Cliff 
mine  is  a splendid  example  of  what  can  be  accomplished  by  local 
enterprise.  This  mine  was  developed  by  the  capital  and  technical 
skill  of  local  men  and  has  been  managed  on  a conservative  basis  to 
the  profit  of  the  stockholders. 

Considexed  in  their  broader  relations  the  auriferous  rocks  of  Valdez 
Inlet  appear  to  form  part  of  a belt  of  more  or  less  altered  sedi- 
ments,® which  extends  northward  to  Klutina  Lake  and  strikes  east- 
ward across  Copper  River  below  Wood  Canyon.  Within  this  belt 
some  placer  gold  has  been  found  on  tributaries  of  Klutina^  and  Ton- 
sina®  rivers. 

East  of  Copper  River  placer  gold  has  been  found  in  the  Brenner 
River  basin,  where  some  auriferous  quartz  is  also  reported,  and  these 
probably  occur  in  the  same  belt  of  rocks,  all  of  which  suggests  that, 
locally  at  least,  these  rocks  are  mineralized  and  justifies  further  pros- 
pecting for  gold. 

McKinley  lake. 

Gold-bearing  veins  have  long  been  known  to  occur  on  and  just  to 
the  northwest  of  McKinley  Lake,  which  empties  into  Alaganik 
Slough,  of  the  Copper  River  Delta.  The  veins  discovered  lie  from 
1 to  2 miles  northeast  and  north  of  Alaganik  station  on  the  Copper 
River  and  Northwestern  Railway  and  about  18  miles  east-southeast 
of  Cordova.  The  bed  rock  of  the  district  is  composed  of  graywacke 
and  soft  black  slate  of  the  Orca  group.  This  locality  was  visited 
by  A.  C.  Spencer  in  1900,  and  he  described  it  as  follows : ® 

At  this  place  several  veins  of  quartz  have  been  opened  and  found  to  contain 
gold  in  varying  quantities.  A short  study  of  this  field  was  sufficient  to  show 
that  the  principal  veins  lie  parallel  to  the  stratification  of  the  sedimentary 
rocks  and  that  they  usually  follow  the  contact  of  two  beds  of  different  char- 

“ Schrader,  F.  C.,  A reconnaissance  of  a part  of  Prince  William  Sound  and  the  Copper 
River  district,  Alaska,  in  1898  : Twentieth  Ann.  Kept.  U.  S.  Geol.  Survey,  pt.  7,  1900,  pp. 
408-410  and  map  No.  21. 

Idem,  p.  422. 

® Schrader,  F.  C.,  and  Spencer,  A.  C.,  The  geology  and  mineral  resources  of  a portion 
of  the  Copper  River  district,  Alaska ; a special  publication  of  the  U.  S.  Geol,  Survey,  1901, 
p.  90. 


76  RECONNAISSANCE  OF  PRINCE  WILLIAM  SOUND,  ALASKA. 

acter,  as  of  massive  arkose  sandstone  against  shale.  In  many  cases  ledges 
varying  in  width  from  a few  inches  to  several  feet  may  be  traced  for  fong 
distances.  In  one  claim  the  quartz  shows  a large  amount  of  free  gold  in  small 
stringers,  hut  this  claim  has  not  been  sufficiently  exploited  to  determine  either 
the  permanence  of  the  vein  or  its  character. 

Besides  these  veins  in  the  planes  of  stratification  there  are  others  transverse 
to  the  bedding  w’hich  have  a width  up  to  4 feet  and  are  known  to  be  continuous 
tor  100  feet  or  more.  One  of  these,  which  shows  no  free  gold,  was  sampled 
and  found  to  contain  0.64  ounce  of  gold.  On  the  whole,  the  Alaganik  region 
seems  worthy  of  the  further  attention  of  mining  men. 

Some  development  work  was  done  in  the  McKinley  Lake  district 
a few  years  ago,  but  the  plants  were  abandoned.  Recently  pros- 
pecting has  been  stimulated  in  this  field  by  new  discoveries,  and  a 
small  stamp  mill  has  been  erected.  The  veins  first  discovered  were 
small  and  carried  free-milling  ore,  while  some  of  the  newer  discov- 
eries are  reported  to  be  larger  veins  carrying  base  ores. 

JACKPOT  BAY. 

For  several  years  there  have  been  reports  of  the  finding  of  “ float  ” 
ore,  carrying  considerable  values  in  gold,  on  the  shores  of  Jackpot 
Bay,  west  of  Chenega  Island.  In  1908  one  vein  carrying  ore  of  this 
character  was  located  on  the  east  side  of  this  bay  near  its  head  (the 
south  end) . The  country  rock  at  this  locality  is  graywacke  and  gray- 
wacke  slate,  with  a general  north-northeasterly  strike,  parallel  with 
the  axis  of  the  bay,  and  a dip  of  40°  to  60°  WNW.  A cpiarter  of  a 
mile  from  the  shore  of  the  bay  and  aproximately  770  feet  above  sea 
level  an  opening  has  been  made  along  a vein.  The  opening  has  pene- 
trated 8 feet  into  the  vein  and  runs  up  the  cliff  side  for  12  feet. 
The  vein  is  a (piartz  vein  and  strikes  N.  52°  W.  and  dips  67°  W. 
It  is,  as  here  exposed,  20  to  28  inches  in  width  and  has  a fairly  well- 
defined  central  zone  which  is  rich  in  metallic  sulphides — arseno- 
jiyrite,  galena,  and  sphalerite.  This  central  zone  is  6 to  11  inches  in 
thickness.  A sample  for  assay  was  taken  three  times  across  the  outer 
})arts  of  the  vein  and  also  three  times  across  the  central,  sulphide 
zone.  The  first  sample  showed  0.5  ounce  of  gold  and  0.3  ounce  of 
silver  to  the  ton,  or  a total  value  of  $11.89  a ton.  The  second  sample 
gave  2.5  ounces  of  gold  and  5.9  ounces  of  silver  to  the  ton,  or  a total 
value  of  $54.73  a ton.®  Although  this  vein  is  small  and  its  extent 
is  not  known,  still  its  gold  content  may  reasonably  encourage  further 
search  for  gold-bearing  veins  in  its  vicinity. 

CONCLUSIONS. 

The  facts  noted  above,  especially  the  results  attained  on  Port 
Valdez,  McKinley  Lake,  and  Ja’clqjot  Bay,  justify  the  opinion  that 
auriferous  quartz  veining  is  not  exceptionally  uncommon  about 
Prince  AVilliam  Sound.  In  one  place,  the  Cliff  mine,  a producing 


“Assays  by  W.  H,  Coghili  and  D.  F.  Higgins,  of  Northwestern  University. 


SILVER. 


77 


property  has  been  developed.  The  facts  are  sufficient  to  encourage 
further  careful  search  for  gold-bearing  quartz  veins  about  Prince 
William  Sound  and  to  justify  a reasonable  expectation  that  produc- 
ing properties  other  than  the  Cliff  mine  may  be  developed.  It  should, 
however,  be  remembered  that  the  proportion  of  veins  carrying  good 
values  in  gold  to  those  carrying  insignificant  values  will  be  large, 
and  that  the  veins  as  far  as  known  are  not  of  large  size  and  so  may 
not  continue  for  considerable  distances. 

The  best  veins  already  discovered  are  quartz  veins  in  the  slates 
and  graywackes  of  the  Valdez  and  Orca  groups.  No  promising  gold 
veins  have  yet  been  found  in  the  greenstones  and  granites  of  the 
sound.  Certain  light-colored  aplitic  dike  rocks  cut  the  slates  and 
graywackes  in  places,  and  locally  these  dikes  are  partly  altered  and 
contain  siderite  and  pyrite  and  also  probably  small  gold  values. 

SILVER. 

The  copper  ores  also  carry  silver  in  small  amounts.  A large  num- 
ber of  assays  show  from  0.16  to  2.24  ounces  of  silver  to  the  ton  of 
ore.  The  average  silver  content  of  these  ores  is  probably  less  than 
1 ounce  to  the  ton. 

No  silver  prospects  have  been  noted  on  the  sound,  and  the  silver 
content  of  the  gold  ore  on  Jackpot  Bay  has  been  given  above. 

NICKEL. 

Prospecting  for  nickel  was  carried  on  in  1905  at  two  points  on  the 
shore  of  Prince  William  Sound.  One  is  on  the  south  side  of  Port 
Valdez,  where  small  stringers  of  pyrrhotite,  possibly  carrying  nickel, 
occur.  The  other  is  on  the  east  shore  of  Unakwik  Inlet,  just  north  of 
the  mouth  of  Miners  River.  There  is  a tunnel  here  8 feet  in  length. 
The  country  rock  is  diorite,  carrying  disseminated  pyrrhotite.  The 
vein,  if  it  can  be  so  called,  is  a zone  in  the  diorite  impregnated  with 
this  iron  sulphide  and  has  no  sharply  defined  walls.  This  sulphide- 
bearing rock  is  10  feet  or  more  in  width,  and  above  the  tunnel,  which 
is  at  the  water’s  edge,  a zone  of  iron-stained  rock,  perhaps  20  feet  in 
width,  can  be  seen  running  up  the  cliff.  Here,  also,  there  are  some 
pegmatitic  veins  in  the  diorite  which  carry  pyrrhotite.  These  peg- 
matitic  veins  are  from  one-fourth  inch  to  2 inches  in  width  and  are 
not  sharply  defined.  There  are  also  in  the  dioritic  country  rock  small 
fractures  filled  with  quartz,  but  these  do  not,  at  least  so  far  as  seen, 
carry  the  iron  sulphide.  It  was  thought  that  the  pyrrhotite  carried 
considerable  values  of  nickel  and  ^Iso  of  cobalt.  Selected  samples  of 
the  best  ore  which  could  be  found  at  this  particular  point  were 
assayed  and  the  results  show  neither  cobalt  or  nickel.  More  work  has 
been  ffqne  here  since  1905,  and  encouraging  results  have  been  reported. 


78  KECONNAISSANCE  OF  PRINCE  WILLIAM  SOUND,  ALASKA. 

ANTIMONY. 

On  the  east  side  of  the  bay  of  Port  Wells,  in  which  is  the  Barry 
Glacier,  about  miles  south  of  the  front  of  this  glacier,  is  an  anti- 
mony prospect.  Near  the  shore  there  are  exposures  of  graywacke 
striking  N.  28°  E.  and  dipping  45°  to  60°  W.  Back  (northeast)  from 
the  shore  about  200  yards  and  100  feet  above  the  sea  a few  small  strip- 
pings have  been  made  on  the  north  side  of  a small  stream.  The  rocks 
here  are  black  slates  and  graywackes,  sheared  and  fractured.  The 
strippings  are  along  a zone  of  highly  sheared  rock.  This  zone  is  6 to 
8 feet  in  thickness,  strikes  N.  68°  E.,  dips  45°  to  65°  N.,  and  is  the 
breccia  along  a thrust  fault.  The  rock  of  this  zone  is  black  slate 
cemented  by  quartz.  On  the  foot-wall  side  of  the  zone  there  is  3 to  4 
inches  of  black  gouge,  and  on  the  hanging  wall  one-half  inch  to  2 
inches  of  the  same  material.  Next  to  the  hanging  wall,  but  in  the 
sheared  zone,  is  a layer,  1 to  8 inches  thick,  of  quartz  holding  less  rock 
than  usual.  This  layer  contains  stibnite  (sulphide  of  antimony), 
which  is  closely  associated  with  the  quartz  and  in  some  places  fills 
little  vugs  in  the  quartz.  Some  movement  has  taken  place  along  the 
fault  since  the  deposition  of  the  quartz  and  stibnite,  as  indicated  by 
slickensided  surfaces.  The  samples  of  this  layer  collected  here  have 
one-tenth  to  one-third  of  their  mass  stibnite.  This  layer  is  reported 
to  have  been  2 feet  thick  in  places  and  to  have  carried  much  more 
stibnite  than  noted  above.  About  1,000  pounds  of  antimony  ore  is 
said  to  have  been  taken  from  this  place. 

LEAD. 

Galena,  the  sulphide  of  lead,  has  been  found  in  very  small  amounts 
with  the  copper  minerals  in  several  localities.  In  none  of  these  places 
is  it  in  large  enough  quantities  to  form  an  ore  of  value.  It  is,  however, 
fairly  abundant  in  the  gold  vein  on  Jackpot  Bay,  already  described. 

ZINC. 

Sphalerite,  the  sulphide  of  zinc,  has  also  been  found  in  small 
amounts  with  the  copper  minerals  in  several  localities.  Some  of  these 
places  are  the  Ellamar  mine;  prospects  just  south  of  Landlocked 
Bay;  prospects  near  the  head  of  Louis  Bay,  in  the  northern  part  of 
Knight  Island ; prospects  on  Herring  Bay  of  Knight  Island.  So  far 
as  present  prospecting  has  gone  no  bodies  of  ore  of  commercial  impor- 
tance have  been  disclosed. 

IRON. 

Iron-bearing  sulphides  (pyrite,  pyrrhotite,  and  chalcopyrite)  occur 
abundantly  about  the  sound,  but  of  course  are  not  of  value  as  iron 
ores. 


MISCELLANEOUS  MINERAL  RESOURCES. 


79 


On  the  northwest  coast  of  Hinchinbrook  Island,  about  miles 
southwest  of  Johnstone  Point,  are  exposures  of  a soft  fine-grained 
slate  or  shale,  gray  to  pinkish  in  color,  which  is  heavily  stained  with 
soft  red  hematite.  Much  of  the  rock  here  resembles  the  “ paint  rock  ” 
of  some  of  the  Lake  Superior  iron  mines,  but  the  hematite  is  only  in 
the  cracks  and  does  not  run  through  the  rock  itself. 

A vein  of  hematite,  2 feet  in  width,  is  reported  from  the  south- 
western part  of  Hinchinbrook  Island,  between  the  south  shore  of  Port 
Etches  and  Signal  Mountain. 

Half  a mile  south  of  Louis  Bay,  in  the  northern  part  of  Knight 
Island,  is  a shear  zone  in  greenstone.  There  are  1 to  10  inches  of  vein 
material  in  this  zone.  The  vein  material  is  magnetite  with  pyrite 
and  a little  epidote  and  pyrrhotite.  The  vein  strikes  northeast  and 
southwest  and  dips  80°  SE. 

ASBESTOS. 

On  the  southeast  side  of  Elrington  Island,  miles  from  the  north- 
east end  of  the  island,  is  about  370  feet  of  tunneling  exposing  some 
quartz  and  calcite  veins  in  greenstone  and  black  to  gray  slate.  These 
veins  hold  a little  pyrrhotite,  but,  as  far  as  seen,  no  asbestos,  although 
the  work  is  reported  to  have  been  done  on  an  asbestos  prospect.  Near 
the  mouth  of  the  tunnel  are  several  fragments  of  greenstone  similar 
to  that  in  place  near  at  hand,  carrying  irregular  veins  of  asbestos 
mixed  with  quartz.  Some  of  these  veins  are  3 inches  in  width  and 
the  fibers  of  the  asbestos  are  perpendicular  to  the  walls  of  the  veins. 

PETROLEUM. 

W.  N.  Armstrong  reports  the  discovery  of  petroleum  seepage  on 
Eyak  River  about  a mile  south  of  the  Copper  River  and  Northwestern 
Railway. 

58668°— Bull.  443—10 6 


RECENT  SURVEY  PUBLICATIONS  ON  ALASKA. 

[Arranged  geographically.  A complete  list  can  be  bad  on  application.] 

All  these  publications  can  be  obtained  or  consulted  in  the  following  ways: 

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GENERAL. 

*The  geography  and  geology  of  Alaska,  a summary  of  existing  knowledge,  by 
A.  H.  Brooks,  with  a section  on  climate,  by  Cleveland  Abbe,  jr.,  and  a 
topographic  map  and  description  thereof,  by  R.  U.  Goode.  Professional 
Paper  45,  1906,  327  pp.  $1. 

Placer  mining  in  Alaska  in  1904,  by  A.  H.  Brooks.  In  Bulletin  259,  1905,  pp. 
18-31. 

The  mining  industry  in  1905,  by  A.  H.  Brooks.  In  Bulletin  284,  1906,  pp.  4-9. 

The  mining  industry  in  1906,  by  A.  H.  Brooks.  In  Bulletin  314,  1907,  pp.  19-39. 

*The  mining  industry  in  1907,  by  A.  H.  Brooks.  In  Bulletin  345,  pp.  30-53.  45 
cents. 

The  mining  industry  in  1908,  by  A.  H.  Brooks.  In  Bulletin  379,  1909,  pp.  21-62. 

The  mining  industry  in  1909,  by  A.  H.  Brooks.  In  Bulletin  442,  1910,  pp.  20-46. 

Railway  routes,  by  A.  H.  Brooks.  In  Bulletin  284,  1906,  pp.  10-17. 

Administrative  report,  by  A.  H.  Brooks.  In  Bulletin  259,  1905,  pp.  13-17. 

Administrative  report,  by  A.  H.  Brooks.  In  Bulletin  284,  1906,  pp.  1-3. 

Administrative  report,  by  A.  H.  Brooks.  In  Bulletin  314,  1907,  pp.  11-18. 

*Administrative  report,  by  A.  H.  Brooks.  In  Bulletin  345,  1908,  pp.  5-17.  45 

cents. 

Administrative  report,  by  A.  H.  Brooks.  In  Bulletin  379,  1909,  pp.  5-20. 
Administrative  report,  by  A.  H.  Brooks.  In  Bulletin  442,  1910,  pp.  5-19. 

Notes  on  the  petroleum  fields  of  Alaska,  by  G.  C.  Martin.  In  Bulletin  259, 
1905,  pp.  128-139. 

The  petroleum  fields  of  the  Pacific  coast  of  Alaska,  with  an  account  of  the 
Bering  River  coal  deposits,  by  G.  C.  Martin.  Bulletin  250,  1905.  64  pp. 
Markets  for  Alaska  coal,  by  G.  C.  Martin.  In  Bulletin  284,  1906,  pp.  18-29. 
The  Alaska  coal  fields,  by  G.  C.  Martin.  In  Bulletin  314,  1907,  pp.  40^6. 
Alaska  coal  and  its  utilization,  by  A.  H.  Brooks.  In  Bulletin  442,  1910, 
pp.  47-100. 

The  possible  use  of  peat  fuel  in  Alaska,  by  C.  A.  Davis.  In  Bulletin  379,  1909. 
pp.  63-66. 

The  preparation  and  use  of  peat  as  a fuel,  by  C.  A.  Davis.  In  Bulletin  442, 
1910,  pp.  101-132. 

*The  distribution  of  mineral  resources  in  Alaska,  by  A.  H.  Brooks.  In  Bulletin 
345,  pp.  18-29.  45  cents. 

Mineral  resources  of  Alaska,  by  A.  H.  Brooks.  In  Bulletin  394,  1909,  pp. 
172-207. 

80 


RECENT  SURVEY  PUBLICATIONS  ON  ALASKA. 


81 


^Methods  and  costs  of  gravel  and  placer  mining  in  Alaska,  by  C.  W.  Purington. 
Rnlletin  203,  1905,  302  pp.  35  cents.  Abstract  in  Bulletin  259,  1905,  pp. 
32-40. 

^Prospecting  and  mining  gold  placers  in  Alaska,  by  J.  P.  Hutchins.  In  Bulletin 
345,  1908,  pp.  54-77.  45  cents. 

Geographic  dictionary  of  Alaska,  by  Marcus  Baker;  second  edition  by  James 
McCormick.  Bulletin  299,  1900,  090  pp. 

* Water-supply  investigations  in  Alaska  in  1900-7,  by  F.  F.  Henshaw  and  C.  C. 
Covert.  Water-Supply  Paper  218,  1908,  150  pp.  25  cents. 

Topographic  waps. 

Alaska,  topographic  map  of ; scale,  1 : 2,500,000.  Preliminary  edition  by  R.  U. 

Goode.  Contained  in  Professional  Paper  45.  Not  published  separately. 
Map  of  Alaska  showing  distribution  of  mineral  resources ; scale,  1 : 5,000,000 ; 

by  A.  H.  Brooks.  Contained  in  Bulletin  345  (in  pocket). 

Map  of  Alaska ; scale,  1 : 5,000,000 ; by  Alfred  H.  Brooks. 

SOUTHEASTERN  ALASKA. 

Preliminary  report  on  the  Ketchikan  mining  district,  Alaska,  with  an  intro- 
ductory sketch  of  the  geology  of  southeastern  Alaska,  by  Alfred  H.  Brooks. 
Professional  Paper  1,  1902,  120  pp. 

*The  Porcupine  placer  district,  Alaska,  by  C.  W.  Wright.  Bulletin  236,  1904, 
35  pp.  15  cents. 

The  Treadwell  ore  deposits,  by  A.  C.  Spencer.  In  Bulletin  259,  1905,  pp.  69-87. 
Economic  developments  in  southeastern  Alaska,  by  F.  E.  and  C.  W.  Wright. 
In  Bulletin  259,  1905,  pp.  47-68. 

The  Juneau  gold  belt,  Alaska,  by  A.  C.  Spencer,  pp.  1-137,  and  A Reconnais- 
sance of  Admiralty  Island,  Alaska,  by  C.  W.  Wright,  pp.  138-154.  Bulletin 
287,  1906,  161  pp. 

Lode  mining  in  southeastern  Alaska,  by  F.  E.  and  C.  W.  Wright.  In  Bulletin 
284,  1906,  pp.  30-53. 

Nonmetallic  deposits  of  southeastern  Alaska,  by  C.  W.  Wright.  In  Bulletin 
284,  1906.  pp.  54-60. 

The  Yakutat  Bay  region,  by  R.  S.  Tarr.  In  Bulletin  284,  1906,  pp.  61-64. 

Lode  mining  in  southeastern  Alaska,  by  C.  W.  Wright.  In  Bulletin  314,  1907, 
pp.  47-72. 

Nonmetalliferous  mineral  resources  of  southeastern  Alaska,  by  C.  W.  Wright. 
In  Bulletin  314,  1907,  pp.  73-81. 

Reconnaissance  on  the  Pacific  coast  from  Yakutat  to  Alsek  River,  by  Eliot 
Blackwelder.  In  Bulletin  314,  1907,  pp.  82-88. 

*Lode  mining  in  southeastern  Alaska  in  1907,  by  C.  W.  Wright.  In  Bulletin 
345,  1908,  pp.  78-97.  45  cents. 

*The  building  stones  and  materials  of  southeastern  Alaska,  by  C.  W.  Wright. 

In  Bulletin  345,  1908,  pp.  116-126.  45  cents. 

*Copper  deposits  on  Kasaan  Peninsula,  Prince  of  Wales  Island,  by  C.  W. 
Wright  and  Sidney  Paige.  In  Bulletin  345,  1908,  pp.  98-115.  45  cents. 

The  Ketchikan  and  Wrangell  mining  districts,  Alaska,  by  F.  E.  and  C.  W. 
Wright.  Bulletin  347,  1908,  210  pp. 

The  Yakutat  Bay  region,  Alaska  : Physiography  and  glacial  geology,  by  R.  S. 
Tarr;  Areal  geology,  by  R.  S.  Tarr  and  B.  S.  Butler.  Professional  Paper 
64,  1909,  186  pp. 

Mining  in  southeastern  Alaska,  by  C.  W.  Wright.  In  Bulletin  379,  1909,  pp. 
67-86. 

Mining  in  southeastern  Alaska,  by  Adolph  Knopf.  In  Bulletin  442,  1910,  pp. 
133-143. 

The  occurrence  of  iron  ore  near  Haines,  by  Adolph  Knopf.  In  Bulletin  442, 
1910,  pp.  144-146. 

A water-power  reconnaissance  in  southeastern  Alaska,  by  J.  C.  Hoyt.  In  Bul- 
letin 442,  1910,  pp.  147-157. 

Topographic  maps. 

Juneau  special  quadrangle;  scale,  1:62,500;  by  W.  J.  Peters.  For  sale  at 
5 cents  each  or  $3  per  hundred. 


82  RECONNAISSANCE  OF  PRINCE  WILLIAM  SOUND,  ALASKA. 


Berners  Bay  special  map;  scale,  1 : 62,500;  by  R.  B.  Oliver.  For  sale  at  5 cents 
each  or  $3  per  hundred. 

Topographic  map  of  the  Juneau  gold  belt,  Alaska.  Contained  in  Bulletin  287, 
Plate  XXXVI,  1906.  Not  issued  separately. 

In  preparation.  ^ 

The  Yakutat  Bay  earthquake  of  September,  1899,  by  R.  S.  Tarr  and  Lawrence 
Martin.  Professional  paper  69. 

Kasaan  Peninsula  special  map;  scale,  1:62,500;  by  D.  C.  Witherspoon,  J.  W. 
Bagley,  and  R.  H.  Sargent. 

Copper  Mountain  special  map ; scale,  1 : 62,500 ; by  R.  H.  Sargent. 

CONTROLLER  BAY,  PRINCE  WILLIAM  SOUND,  AND  COPPER  RIVER  REGIONS. 

*The  mineral  resources  of  the  Mount  Wrangell  district,  Alaska,  by  W.  C. 
Mendenhall.  Professional  i)aper  15,  1903,  71  pp.  Contains  general  map  of 
Prince  William  Sound  and  Copper  River  region ; scale,  12  miles  = 1 inch. 
Bering  River  coal  field,  by  G.  C.  Martin.  In  Bulletin  259,  1905,  pp.  140-150. 
Cape  Yaktag  placers,  by  G.  C.  Martin.  In  Bulletin  259,  1905,  pp.  88-89. 

Notes  on  the  petroleum  fields  of  Alaska,  by  G.  C.  Martin.  In  Bulletin  259, 
1905,  pp.  128-139.  Abstract  from  Bulletin  250. 

The  petroleum  fields  of  the  Pacific  coast  of  Alaska,  with  an  account  of  the 
Bering  River  coal  deposits,  by  G.  C.  Martin.  Bulletin  250,  1905,  64  pp. 
Geology  of  the  central  Copper  River  region,  Alaska,  by  W.  C.  Mendenhall. 
Professional  paper  41,  1905,  133  pp. 

Copper  and  other  mineral  resources  of  Prince  William  Sound,  by  U.  S.  Grant. 
In  Bulletin  284,  1906,  pp.  78-87. 

Distribution  and  character  of  the  Bering  River  coal,  by  G.  C.  Martin.  In 
Bulletin  284,  1906,  pp.  65-76. 

Petroleum  at  Controller  Bay,  by  G.  C.  Martin.  In  Bulletin  314, 1907,  pp.  89-103. 
Geology  and  mineral  resources  of  Controller  Bay  region,  by  G.  C.  Martin. 
Bulletin  335,  1908,  141  pp. 

*Notes  on  copper  prospects  of  Prince  William  Sound,  by  F.  II.  Moffit.  In 
Bulletin  345,  1908,  pp.  176-178.  45  cents. 

*Mineral  resources  of  the  Kotsina  and  Chitina  valleys.  Copper  River  region, 
by  F.  H.  Mofiit  and  A.  G.  Maddren.  In  Bulletin  345,  1908,  pp.  127-175.  45 

cents. 

Mineral  resources  of  the  Kotsina-Chitina  region,  by  F.  H.  Moffit  and  A.  G. 
Maddren.  Bulletin  374,  1909,  103  pp. 

Copper  mining  and  prospecting  on  Prince  William  Sound,  by  U.  S.  Grant  and 
I).  F.  Higgins,  jr.  In  Bulletin  379,  1909,  pp.  87-96. 

Gold  on  Prince  William  Sound,  by  U.  S.  Grant.  In  Bulletin  379,  1909,  p.  97. 
Mining  in  the  Kotsina-Chitina,  Chistochina,  and  Valdez  Creek  regions,  by 
F.  H.  Moffit.  In  Bulletin  379,  1909,  pp.  153-160. 

Mineral  resources  of  the  Nabesna-White  River  district,  by  F.  H.  Moffit  and 
Adolph  Knopf.  In  Bulletin  379,  1909,  pp.  161-180. 

Mineral  resources  of  the  Nabesna-White  River  district,  by  F.  H.  Moffit  and 
Adolph  Knopf;  with  a section  on  the  Quaternary,  by  S.  R.  Capps.  Bulletin 
417,  1910,  64  pp. 

Mining  in  the  Chitina  district,  by  F.  II.  IMoffit.  In  Bulletin  442,  1910,  pp. 
158-163. 

Mining  and  prospecting  on  Prince  William  Sound,  by  U.  S.  Grant.  In  Bulle- 
tin 442,  1910,  pp.  164-165. 


Topographic  maps. 

Map  of  Mount  Wrangell;  scale,  12  miles  = 1 inch.  Contained  in  Professional 
Paper  15.  Not  issued  separately. 

Copper  and  upper  Chistochina  rivers,  scale,  1 : 250,000;  by  T.  G.  Gerdine.  Con- 
tained in  Professional  Paper  41.  Not  issued  separately. 

Copper,  Nabesna,  and  Chisana  rivers,  headwaters  of;  scale,  1 : 250,000;  by  D.  C. 
Witherspoon.  Contained  in  Professional  Paper  41.  Not  issued  separately. 

Controller  Bay  region  special  map;  scale,  1:62,500;  by  E.  G.  Hamilton.  For 
sale  at  35  cents  a copy  or  $21  per  hundred. 

General  map  of  Alaska  coast  region  from  Yakutat  Bay  to  Prince  William 
Sound;  scale,  1:1,200,000;  compiled  by  G.  C.  Martin.  Contained  in  Bulle- 
tin 335. 


RECENT  SURVEY  PUBLICATIONS  ON  ALASKA. 


83 


In  preparation. 

Cbitiim  quadrangle  map;  scale,  1 : 250,000;  by  T.  G.  Gerdiiie  and  D.  C.  Witber- 
siioon. 

COOK  INLET  AND  SUSITNA  REGION. 

Tbe  petroleum  fields  of  tbe  Pacific  coast  of  Alaska,  with  an  account  of  tbe 
Bering  River  coal  deposits,  by  G.  C,  Martin.  Bulletin  250,  1905,  64  pp. 

Coal  resources  of  soutbwestern  Alaska,  by  R.  W.  Stone.  In  Bulletin  259,  1905, 
pp.  151-171. 

Gold  placers  of  Turnagain  Ann,  Cook  Inlet,  by  F.  H.  Moffit.  In  Bulletin  259, 
1905,  pp.  90-99. 

Mineral  resources  of  tbe  Kenai  Peninsula  ; Gold  fields  of  tbe  Turnagain  Arm 
region,  by  F.  H.  Moffit,  pp.  1-52;  Coal  fields  of  the  Kachemak  Bay  region, 
by  R.  W.  Stone,  pp.  53-73.  Bulletin  277,  1906,  SO  pp. 

Preliminary  statement  on  tbe  Matanuska  coal  field,  by  G.  C.  Martin.  In  Bulle- 
tin 284,  1906,  pp.  88-100. 

*A  reconnaissance  of  tbe  Matanuska  coal  field,  Alaska,  in  1905,  by  G.  C.  Martin. 
Bulletin  289,  1906,  36  pp. 

Reconnaissance  in  tbe  Matanuska  and  Talkeetna  basins,  by  Sidney  Paige  and 
Adolph  Knopf.  In  Bulletin  314,  1907,  pp.  104-125. 

Geologic  reconnaissance  in  tbe  IMatanuska  and  Talkeetna  basins,  Alaska,  by 
Sidney  Paige  and  Adolph  Knopf.  Bulletin  327,  1907,  71  pp. 

Notes  on  geology  and  mineral  prospects  in  tbe  vicinity  of  Seward,  Kenai 
Peninsula,  by  U.  S.  Grant  and  D.  F.  Higgins.  In  Bulletin  379, 1909,  pp.  98-107. 

Preliminary  report  on  the  ndneral  resources  of  tbe  southern  part  of  Kenai 
Peninsula,  by  IJ.  S.  Grant  and  D.  F.  Higgins.  In  Bulletin  442,  1910,  pp. 
166-178. 

Outline  of  tbe  geology  and  mineral  resources  of  tbe  Ilianma  and  Clark  lakes 
region,  by  G.  C.  Martin  and  F.  J.  Katz.  In  Bulletin  442,  1910,  pp.  179-200. 

Gold  placers  of  tbe  Mulcbatna,  by  F.  J.  Katz.  In  Bulletin  442,  1910,  pp. 
201-202. 

Topographic  maps. 

Kenai  Peninsula,  northern  portion;  scale,  1 : 250,000;  by  E.  G.  Hamilton.  Con- 
tained in  Bulletin  277.  Not  published  separately. 

Reconnaissance  map  of  Matanuska  and  Talkeetna  region;  scale,  1:250,000; 
by  T.  G.  Gerdine  and  R.  II.  Sargent.  Contained  in  Bulletin  327.  Not  pub- 
lished separately. 

Mount  McKinley  region;  scale,  1:625,000;  by  D.  L.  Reaburn.  Contained  in 
Professional  Paper  45.  Not  published  separately. 

1 71  preparation. 

Tbe  Mount  McKinley  region,  by  A.  II.  Brooks,  with  descriptions  of  tbe  igneous 
rocks  and  of  tbe  Bonnifield  and  Kantisbna  districts  by  L.  M.  Prindle.  Pro- 
fessional Paper  70. 

ALASKA  PENINSULA  AND  ALEUTIAN  ISLANDS. 

Gold  mine  on  Unalaska  Island,  by  A.  J.  Collier.  In  Bulletin  259,  1905,  pp. 
102-103. 

Gold  deposits  of  tbe  Sbumagin  Islands,  by  G.  C.  Martin.  In  Bulletin  259,  1905, 
pp.  100-101. 

Notes  on  tbe  petroleum  fields  of  Alaska,  by  G.  C.  Martin.  In  Bulletin  259, 
1905,  pp.  128-139.  Abstract  from  Bulletin  250. 

Tbe  petroleum  fields  of  tbe  Pacific  coast  of  Alaska,  with  an  account  of  tbe 
Bering  River  coal  deposits,  by  G.  C.  Martin.  In  Bulletin  250,  1905,  64  pp. 

Coal  resources  of  soutbwestern  xVlaska,  by  R.  W.  Stone.  In  Bulletin  259,  1905. 
pp.  151-171. 

Tbe  Herendeen  Bay  coal  field,  by  Sidney  Paige.  In  Bulletin  284,  1906,  pp. 
101-108. 

Mineral  resources  of  soutbwestern  Alaska,  by  W.  AV.  Atwood.  In  Bulletin 
379,  1909,  pp.  108-152. 

In  pr'eparation. 

Geology  and  mineral  resources  of  parts  of  Alaska  Peninsula,  by  W.  W.  At- 
wood. 


84  RECONNAISSANCE  OF  PRINCE  WILLIAM  SOUND,  ALASKA. 


YUKON  BASIN. 

The  coal  resources  of  the  Yukon,  Alaska,  by  A.  J.  Collier.  Bulletin  218,  1903, 
71  pp. 

*The  gold  placers  of  the  Fortymile,  Birch  Creek,  and  Fairbanks  regions,  by 
L.  M.  Prindle.  Bulletin  251,  1905,  89  pp.  35  cents. 

Yukon  placer  fields,  by  L.  M.  Prindle.  In  Bulletin  284,  1906,  pp.  109-131. 
Reconnaissance  from  Circle  to  Fort  Hamlin,  by  R.  W.  Stone.  In  Bulletin  284, 
1906,  pp.  128-131. 

The  Yukon-Tanana  region,  Alaska ; description  of  the  Circle  quadrangle,  by 
L.  M.  Prindle.  Bulletin  295,  1906,  27  pp. 

The  Bonnifield  and  Kantishna  regions,  by  L.  M.  Prindle.  In  Bulletin  314,  1907, 
pp.  205-226. 

The  Circle  precinct,  Alaska,  by  Alfred  II.  Brooks.  In  Bulletin  314,  1907,  pp. 
187-204. 

The  Yukon-Tanana  region,  Alaska  ; description  of  the  Fairbanks  and  Rampart 
quadrangles,  by  L.  M.  Prindle,  F.  L.  Hess,  and  C.  C.  Covert.  Bulletin  337, 

1908,  102  pp. 

♦Occurrence  of  gold  in  the  Yukon-Tanana  region,  by  L.  M.  Prindle.  In  Bulletin 
345,  1908,  pp.  179-186.  45  cents. 

♦The  Fortymile  gold  placer  district,  by  L.  M.  Prindle.  In  Bulletin  345,  1908, 
pp.  187-197.  45  cents. 

Water-supply  investigations  in  Alaska,  1906  and  1907,  by  F.  F.  Henshaw  and 
C.  C.  Covert.  Water-Supply  Paper  218,  1908,  156  pp. 

♦Water  supply  of  the  Fairbanks  district  in  1907,  by  C.  C.  Covert.  In  Bulletin 
345,  1908,  pp.  198-205.  45  cents. 

The  Fortymile  quadrangle,  by  L.  M.  Prindle.  Bulletin  375,  1909,  52  pp. 
Water-supply  investigations  in  Yukon-Tanana  region,  1906-1908,  by  C.  C. 

Covert  and  C.  E.  Ellsworth.  Water-Supply  Paper  228,  1909,  108  pp. 

The  Fairbanks  gald-placer  region,  by  L.  M.  Prindle  and  F.  J.  Katz.  In  Bul- 
letin 379,  1909,  pp.  181-200. 

Water  supply  of  the  Yukon-Tanana  region,  1907-8,  by  C.  C.  Covert  and  C.  E. 

Ellsworth.  In  Bulletin  379,  1909,  pp.  201-228. 

Gold  placers  of  the  Ruby  Creek  district,  by  A.  G.  Maddren.  In  Bulletin  379, 

1909,  pp.  229-233. 

Placers  of  the  Gold  Plill  district,  by  A.  G.  Maddren.  In  Bulletin  379,  1909, 
pp.  234-237. 

Gold  placers  of  the  Innoko  district,  by  A.  G.  Maddren.  In  Bulletin  379,  1909, 
pp.  238-266. 

The  Innoko  gold-placer  district,  with  accounts  of  the  central  Kuskokwim 
A^alley  and  the  Ruby  Creek  and  Gold  Hill  placers,  by  A.  G.  Maddren. 
Bulletin  410,  1910,  87  pp. 

Sketch  of  the  geology  of  the  northeastern  part  of  the  Fairbanks  quadrangle, 
by  L.  M.  Prindle.  In  Bulletin  442,  1910,  pp.  203-209. 

The  auriferous  quartz  veins  of  the  Fairbanks  district,  by  L.  M.  Prindle.  In 
Bulletin  442,  1910,  pp.  210-229. 

Placer  mining  in  the  Yukon-Tanana  region,  by  C.  E.  Ellsworth.  In  Bulletin 
442,  1910,  pp.  230-245. 

Occurrence  of  wolframite  and  cassiterite  in  the  gold  placers  of  Deadwood 
Creek,  Birch  Creek  district,  by  B.  L.  Johnson.  In  Bulletin  442,  1910, 
pp.  246-250. 

Water  supply  of  the  Yukon-Tanana  region,  1909,  by  C.  E.  Ellsworth.  In 
Bulletin  442.  1910,  pp.  251-283. 

The  Koyukuk-Chaudalar  gold  region,  by  A.  G.  Maddren.  In  Bulletin  442, 

1910,  pp.  284-315. 

Topographic  maps. 

Fortymile  quadrangle ; scale,  1 : 250,000 ; by  E.  C.  Barnard.  For  sale  at  5 
cents  a copy  or  $3  per  hundred. 

The  Fairbanks  quadrangle ; scale,  1 : 250,000 ; by  T.  G.  Gerdine,  D.  C.  Wither- 
spoon, and  R.  B.  Oliver.  For  sale  at  10  cents  a copy  or  $6  per  hundred. 
Rampart  quadrangle;  scale,  1:250,000;  by  D.  C.  Witherspoon  and  R.  B. 

Oliver.  For  sale  at  10  cents  a copy  or  $6  per  hundred. 

Fairbanks  special  map;  scale,  1:62,500;  by  T.  G.  Gerdine  and  R.  H.  Sargent. 

For  sale  at  10  cents  a copy  or  $6  per  hundred. 

Yukon-'l''anana  region,  reconnaissaiice  map  of;  scale,  1:625,000.;  by  T.  G. 
Gerdine.  Contained  in  Bulletin  251,  1905.  Not  published  separately. 


RECENT  SURVEY  PUBLICATIONS  ON  ALASKA. 


85 


Fairbanks  and  Birch  Creek  districts,  reconnaissance  maps  of;  scale,  1 : 250,000; 

by  T,  G.  Gerdine.  Contaiiied  in  Bulletin  251,  1905.  Not  issued  separately. 
Circle  quadrangle,  Yukon-Tanana  region;  scale,  1:250,000;  by  D.  C.  Wither- 
si)oon.  Contained  in  Bulletin  295.  In  print  as  separate  publication. 

In  preparation. 

Geology  and  mineral  resources  of  Fairbanks  quadrangle,  by  L.  M.  Prindle. 


SEWARD  PENINSULA. 

A reconnaissance  of  the  Cape  Nome  and  adjacent  gold  fields  of  Seward  Penin- 
sula, Alaska,  in  1900,  by  A.  H.  Brooks,  G.  B.  Richardson,  and  A.  J.  Collier. 
In  a special  publication  entitled  “ Reconnaissances  in  the  Cape  Nome  and 
Norton  Bay  regions,  Alaska,  in  1900,”  1901,  180  pp. 

A reconnaissance  in  the  Norton  Bay  region,  Alaska,  in  1900,  by  W.  C.  Menden- 
hall. In  a special  publication  entitled  “ Reconnaissances  in  the  Cape 
Nome  and  Norton  Bay  regions,  Alaska,  in  1900.” 

A reconnaissance  of  the  northwestern  portion  of  Seward  Peninsula,  Alaska,  by 
A.  J.  Collier.  Professional  Paper  2,  1902,  70  pp. 

The  tin  deposits  of  the  York  region,  Alaska,  by  A.  J.  Collier.  Bulletin  229, 
1904,  61  pp. 

Recent  developments  of  Alaskan  tin  deposits,  by  A.  J.  Collier.  In  Bulletin 
259,  1905,  pp.  120-127. 

The  Fairhaven  gold  placers  of  Seward  Peninsula,  by  F.  H.  Moffit.  Bulletin 
247,  1905,  85  pp. 

The  York  tin  region,  by  F.  L.  Hess.  In  Bulletin  284,  1906,  pp.  145-157. 

Gold  mining  on  Seward  Peninsula,  by  F.  H.  Moffit.  In  Bulletin  284,  1906, 
pp.  132-141. 

The  Kougarok  region,  by  A.  H.  Brooks.  In  Bulletin  314,  1907,  pp.  164-181. 
*\Vater  supply  of  Nome  region,  Seward  Peninsula,  Alaska,  1906,  by  J.  C.  Hoyt 
and  F.  F.  Henshaw.  Water-Supply  Paper  196,  1907,  52  pp.  15  cents. 
Water  supply  of  the  Nome  region,  Seward  Peninsula,  1906,  by  J.  C.  Hoyt  and 
F.  F.  Henshaw.  In  Bulletin  314,  1907,  pp.  182-186. 

The  Nome  region,  by  F.  H.  Moffit.  In  Bulletin  314,  1907,  pp.  126-145. 

Gold  fields  of  the  Solomon  and  Ninkluk  river  basins,  by  P,  S.  Smith.  In 
Bulletin  314,  1907,  pp.  146-156. 

Geology  and  mineral  resources  of  Iron  Creek,  by  P.  S.  Smith.  In  Bulletin  314, 

1907,  pp.  157-163. 

The  gold  placers  of  parts  of  Seward  Peninsula,  Alaska,  including  the  Nome, 
Council,  Kougarok,  Port  Clarence,  and  Goodhope  precincts,  by  A.  J.  Collier, 
F.  L.  Hess,  P.  S.  Smith,  and  A.  H.  Brooks.  Bulletin  328,  1908,  pp.  343. 
'^Investigation  of  the  mineral  deposits  of  Seward  Peninsula,  by  P.  S.  Smith. 

In  Bulletin  345,  1908,  pp.  206-250.  45  cents. 

*The  Seward  Peninsula  tin  deposits,  by  Adolph  Knopf.  In  Bulletin  345,  1908, 
pp.  251-267.  45  cents. 

^Mineral  deposits  of  the  Lost  River  and  Brooks  Mountain  regions,  Seward 
Peninsula,  by  Adolph  Knopf.  In  Bulletin  345,  1908,  pp.  268-271.  45  cents. 

*Water  supply  of  the  Nome  and  Kougarok  regions,  Seward  Peninsula,  in  1906-7, 
by  F.  F.  Henshaw.  In  Bulletin  345,  1908,  pp.  272-285.  45  cents. 
Water-supply  investigations  in  Alaska,  1906  and  1907,  by  F.  F.  Henshaw  and 
C.  C.  Covert.  Water-Supply  Paper  218,  1908,  pp.  156. 

Geology  of  the  Seward  Peninsula  tin  deposits,  by  Adolph  Knopf.  Bulletin  358, 

1908,  pp.  72. 

Recent  developments  in  southern  Seward  Peninsula,  by  P.  S.  Smith.  In  Bulle- 
tin 379,  1909,  pp.  267-301. 

The  Iron  Creek  region,  by  P.  S.  Smith.  In  Bulletin  379,  1909,  pp.  302-354. 
Mining  in  the  Fairhaven  precinct,  by  F.  F.  Henshaw.  In  Bulletin  379,  1909, 
pp.  355-369. 

Water-supply  investigations  in  Seward  Peninsula  in  1908,  by  F.  F.  Henshaw. 
In  Bulletin  379,  1909,  pp.  370-401. 

Geology  and  mineral  resources  of  the  Solomon  and  Casadepaga  quadrangles, 
Seward  Peninsula,  by  P.  S.  Smith.  Bulletin  433,  1910,  234  pp. 

Mineral  resources  of  the  Nulato-Council  region,  by  P,  S.  Smith  and  H.  M. 
Eakin.  In  Bulletin  442,  1910,  pp.  316-352. 


86  RECONNAISSANCE  OF  PRINCE  WILLIAM  SOUND,  ALASKA. 


Mining  in  Seward  Peninsula,  by  F.  F.  Hensbaw.  In  Bulletin  442,  1910, 
pp.  358-371. 

Water-supply  investigations  in  Seward  Peninsula  in  1909,  by  F.  F.  Hensbaw. 
In  Bulletin  442,  1910,  pp.  372-418. 

Topographic  maps. 

Tbe  following  maps  are  for  sale  at  5 cents  a copy,  or  $3  per  bundred : 

Casadepaga  quadrangle,  Seward  Peninsula;  scale,  1:62,500;  by  T.  G.  Gerdine. 

Grand  Central  special,  Seward  Peninsula  ; scale,  1 : 62,500 ; by  T.  G.  Gerdine. 

Nome  special,  Seward  Peninsula;  scale,  1:62,500;  by  T.  G.  Gerdine. 

Solomon  quadrangle,  Seward  Peniusula ; scale,  1:62,500;  by  T.  G.  Gerdine. 

Tbe  following  maps  are  for  sale  at  25  cents  a copy,  or  $15  per  bundred : 

Seward  Peninsula,  nortbeastern  portion  of,  topographic  reconnaissance  of; 
scale,  1 : 250,000 ; by  T.  G.  Gerdine. 

Seward  l*eninsula,  northwestern  portion  of,  topographic  reconnaissance  of; 
scale,  1 : 250,000 ; by  T.  G.  Gerdine. 

Seward  Peninsula,  southern  portion  of,  topographic  reconnaissance  of;  scale, 
1:250,000;  by  T.  G.  Gerdine. 

In  preparation. 

Geology  of  tbe  area  represented  on  tbe  Nome  and  Grand  Central  special  maps ; 
by  F.  H.  Moflit,  F.  L.  Hess,  and  P.  S.  Smith. 

Tbe  water  resources  of  Seward  Peniusula ; by  F.  F.  Hensbaw. 

NORTHERN  ALASKA. 

A reconnaissance  from  Fort  Hamlin  to  Kotzebue  Sound,  Alaska,  by  way  of 
Dali,  Kanuti,  Allen,  and  Kowak  rivers;  by  W.  C.  Mendenhall.  Professional 
Paper  10,  1902,  pp.  68. 

““bA  reconnaissance  in  northern  Alaska  across  tbe  liocky  Mountains,  along  tbe 
Koyukuk,  John,  Anaktuvuk,  and  Colville  rivers,  and  tbe  Arctic  coast  to 
Cape  Lisburne,  in  1901 ; by  F.  C.  Schrader  and  W.  J.  Peters.  Professional 
Paper  20,  1904,  pp.  139. 

Coal  belds  of  tbe  Cape  Lisburne  region ; by  A.  J.  Collier.  In  Bulletin  259,  1905, 
pp.  172-185. 

Geology  and  coal  resources  of  Cape  Lisburne  region,  Alaska ; by  A.  J.  Collier. 
Bulletin  278,  1906,  pp.  54. 


Topographic  maps. 

Fort  Yukon  to  Kotzebue  Sound,  reconnaissance  map  of;  scale,  1:1,200,000; 
by  D.  L.  Reaburn.  Contained  in  Professional  Paper  10.  Not  published 
separately. 

Koyukuk  River  to  mouth  of  Colville  River,  including  John  River ; scale, 
'1:1,200,000;  by  W.  J.  Peters.  Contained  in  Professional  Paper  20.  (Out 
of  stock.)  Not  published  separately. 


INDEX. 


A. 

Page. 

Acidic  dikes,  occurrence  and  character  of.  20,4(1-48 

Acknowledgments  to  those  aiding 13 

Amphibole,  photomicrograph  of 36 

Antimony,  occurrence  of 78 

Asbestos,  occurrence  of 79 

B. 

Barry  Glacier,  dikes  at 47 

Basic  intrusive  rocks,  occurrence  and  char- 
acter of 20, 48-51 

relations  of,  to  copper 58 

Betties,  J.  J.,  acknowledgments  to 13 

Bligh  Island,  rocks  near 28 

Bonanza  copper  mine,  description  of 63 

location  of 12, 52 

ores  of : 56, 58, 65 

plans  and  section  of,  figures  showing 64, 65 

rock  at,  analysis  of 65 

views  at 64 

Boulder  Bay,  copper  mining  at 61 

Brenner  River  basin,  gold  in 75 

Brooks,  Alfred  H,,  on  Port  Valdez  gold  oc- 
currences   72-75 

preface  by 7-8 

C. 

Cedar  Bay  granite,  analyses  of 46 

occurrence  and  character  of 41-43 

Chalcopyrite,  occurrence  and  character  of 53 

Chugach  Gulf,  present  name  of 2 

Chugach  Mountains,  description  of 14-15 

Cirques,  occurrence  of 19 

Cliff  gold  mine,  description  of 72-74 

Columbia  Bay,  view  at 18 

Columbia  Glacier,  location  and  character  of. . 20 

Copper,  derivation  of 8 

exploitation  of 52-53 

occurrence  of 12 

ores  of 53-59 

origin  of 8,57-59 

production  of 53 

prospecting  for 70-71 

Copper  Bullion  claims,  description  of 69 

Copper  mines,  descriptions  of 59-70 

location  of 12, 52 

Copper  mining,  prospects  of 70 

Cordova,  description  of 11 

views  from 14 

Cordova  Copper  Co.,  work  of 70 

Cordova-Tacoma  Copper  Co.,  work  of 70 

Culross  Island,  granite  on 37-38 

D. 

Diabase,  occurrence  and  character  of 20, 50-51 

Dikes,  acidic,  occurrence  and  character  of.  20, 46-48 
Diorite,  occurrence  and  character  of 20 


Economic  geology,  account  of 52-79 

Ellamar,  copper  mining  near 59-61 

rocks  near 28 

Ellamar  copper  mine,  description  of 59-61 

location  of 12,52 

ores  of 56 

views  of 60 

workings  of,  plan  showing 60 

Ellipsoidal  greenstones,  occurrence  and  char- 
acter of 51-52 

views  of 26 

Elrmgton  Island,  rocks  of 31 

Eshamy  granite,  occurrence  and  character  of.  34-35 

photomicrographs  of 36 

Esther  granite,  analyses  of 46 

occurrence  and  character  of 39-41 

photomicrograph  of 36 

Esther  Island,  gabbro  on 49 

Explorations,  progress  of 12-13 

Ewan  Bay,  granite  on 34 

F. 

Faults,  effect  of,  on  topography 16 

Fidalgo-Alaska  Copper  Co.,  mine  of 63 

Fidalgo  Bay,  copper  mining  at 62 

view  near 16 

Fidalgo  Bay  Mining  Co.,  mme  of 63 

Field  work,  extent  of 7 

Flats,  location  and  character  of 16-17 

view  of 16 

G. 

Gabbro,  occurrence  and  character  of 20,  49-50 

Galena,  occurrence  of 54 

Galena  Bay,  copper  mining  on 59 

rocks  on • 20-28 

section  on,  figure  showing 27 

Galena  Bay  Mining  Co.,  mine  of 59 

Geography,  description  of 9,11 

Geologic  map  of  Latouche  Island Pocket. 

of  Prince  William  Sound Pocket. 

preparation  of 13 

Geology,  descriptive,  account  of 20-52 

outline  of 11-12 

Geology,  economic,  account  of 52-79 

Giant  Rocks,  dikes  at 48 

Glaciation,  description  of 18-20 

evidences  of,  view  of 18 

Glacier  Bay,  granite  on 44 

Gold,  occurrence  of,  description  of 72-77 

occurrence  of,  methods  of 71-72 

production  of 53, 71 

prospects  of 76-77 

Granite,  analyses  of 45 

composition  of 44-46 


87 


88 


INDEX. 


Pago. 

Granite,  occurrence  and  character  of 20,33-46 

photomicrographs  of 36 

Grant,  U.  S.,  work  of 13 

Graywacke,  occurrence  and  character  of 20-21 

view  of 24 

Greenstone,  occurrence  and  character  of 51-52 

views  of 26 

Gull  Island,  view  on 24 


H. 

Happy  Jack  Copper  Mining  and  Develop- 


ment Co.,  mine  of 68-69 

section  of,  figure  showing 69 

Ilarriman  Alaska  Expedition,  on  Prince 

William  Sound 12-13,32 

Ilarriman  Fiord,  dikes  on 47 

Hematite,  occurrence  of 79 

Hoodoo  Island,  rocks  of 31 

I. 

Igneous  rocks,  description  of 20, 33-52 

Iron,  occurrence  of 78-79 

J. 

Jackpot  Bay,  gold  mines  on 76 

lead  at 76,78 

K. 

Kindle,  E.  M.,  fossils  determined  by 33 

Knight  Island,  copper  mines  on 56,67-70 

rocks  of. 28 

views  on 16, 18 

Knight  Island  Consolidated  Copper  Co., 

mine  of 67-69 

Knight  Island  Mining  and  Development  Co., 

mine  of 69-70 

Knowlton,  F.  H.,  fossils  determined  by 23 

L. 

Landlocked  Bay,  copper  mining  at 61-62 

views  on  and  near 16, 60 

Latouche  Copper  Mining  Co.,  mme  of 67 

Latouche  Island,  copper  mines  on 63-67 

gabbro  on 49-50 

glaciation  on 19 

investigations  on 7 

rocks  of 29-31 

map  of 29 

sections  on,  figures  showing 29,30 

views  on 64 

Lead,  occurrence  of 78 

Level,  changes  in 17-18 

M. 

McKinley  Lake,  gold  mines  on 75-76 

Map,  of  Latouche  Island Pocket. 

of  Prince  William  Sound 10 

key  to 10 

Map,  geologic,  of  Latouche  Island Pocket. 

of  Prince  William  Sound Pocket. 

preparation  of 13 


Mendenhall,  W.  C.,  on  Prince  William  Sound.  12 


Page. 

Mineral  deposits,  character  of 12 

Minerals,  occurrence  and  character  of,  with 

copper 53-54 

Moifit,  F.  H.,  on  Prince  William  Sound 13 

N. 

Nellie  Juan  granite,  analyses  of 45 

occurrence  and  character  of 37 

Nickel,  occurrence  of 77 

Nikolai  greenstone,  correlation  of 8 

O. 

Orca,  copper  near 56-57,58,70 

Orca  group,  age  of 32 

fossils  in 32 

occurrence  and  character  of 7-8, 11, 21, 25-31 

view  of 24i 

Orca  Inlet,  copper  mines  on 70 

Orthoclase,  photomicrograph  of 36 

P. 

Paddy  Bay,  granite  at 34 

Paige,  Sidney,  work  of 13 

Passage  Canal,  granite  on 38-39 

Petroleum,  occurrence  of 79 

Port  Bainbridge,  granite  on 44 

Port  Gravina,  granite  on 43 

Port  Valdez,  gold  at 72-75 

nickel  at 77 

Port  Valdez  Fiord,  description  of 15 

Port  Wells,  antimony  at 78 

Port  Wells  Fiord,  description  of 15 

Prince  W illiam  Sound  Mining  Co. , mine  of . . . 59 

Pyrite,  occurrence  and  character  of 53 

Pyrrhotite,  occurrence  and  character  of 53 

Q. 

Quartz  porphyry,  photomicrograph  of 36 

R. 

Railways,  routes  of 11 

Reynolds- Alaska  Development  Co.,  mines 

of 61,66-67 

plan  of,  figure  showing 66 

Rocky  Point,  views  at 24,26 


S. 

Schrader,  F.  C.,  on  Prince  William  Sound...  12, 

23,32,48 

Schrader,  F.  C.,  and  Spencer,  A.  C.,  on  Prince 


William  Sound 13,24,32 

Sedimentary  rocks,  description  of 20-33 

Settlements,  description  of 11 

Sheep  Bay  granite,  analyses  of 45 

occurrence  and  character  of 43-44 

Silver,  occurrence  of 77 

production  of 53 

Slate,  occurrence  and  character  of 20-21 

view  of 24 

Spencer,  A.  C.,  on  McKinley  Lake 75-76 

Spencer,  A.  C.,  and  Schrader,  F.  C.,  on  Prince 

William  Sound 13,24,32 

Sphalerite,  occurrence  of 56 


INDEX, 


89 


Page. 


Standard  Copper  Mines  Co.,  mine  of 02 

plant  of,  view  of (iO 

Structure,  description  of 21-22 

effect  of,  on  topography 15-16 

Sunrise  series,  correlatioir  of 24 

occurrence  and  character  of 24 

T. 

Tatitlek  Narrows,  diabase  in 50 

Three  Giants,  view  of 18 

Three  Man  Mining  Co.,  mine  of 62 

Toboggan  Glacier,  dike  at 47 

Topography,  changes  in 17-18 

description  of 14-20 

U. 

Ulrich,  E.  O.,  on  Yakutat  series 33 

Unakwik  Inlet,  diabase  on 50-51 

dikes  on 47-48 

nickel  at 77 


V.  Page. 

Valdez,  description  of 11 

Valdez  group,  age  of 21,23-24 

correlation  of 24 

fossils  in 23-24 

occurrence  and  character  of 7-8, 11, 21, 22-23 

structure  of 23 

Valdez  Inlet,  gold  on 75 

Valdez  Narrows,  dikes  at 48,50 

Valleys,  location  and  character  of 15-16 

Van  Hise,  C.  R.,  cited 49 

Vesuvius  Valley,  copper  mining  in 59 

W. 

Wells  Bay,  granite  on 41-43 

Whalen  and  Nelson  prospect,  description  of..  62-63 

Y. 

Yakutat  series,  occurrence  and  character  of . . 33 

Z. 

Zinc,  occurrence  of 78 


o 


I 


